my 1992 gmc sierra

jdog1

New member
hello,
This is my first time posting here, Ive been lurking for a long time but never posting.This is my first truck.a 1992 GMC Sierra I call Grand Marshall Charles.... its a single cab long bed, with a 350 small block,4x4 and it came with a towing package from the factory. I want to put a bed platform in it for some expedition type trips. Can anyone who has built one before help me out and provides some tips/ideas?
Photo04061645_1.jpg

P.s. ill upload some better pics when I get home.

Many Thanks,
Jdog
 

underdrive

jackwagon
No tips on the platform, but that's a pretty nice truck you got there, 3/4-ton maybe (2500-series)? The 350 engine should you plenty of power AND fuel economy, both of which are needed for just getting out there and going places. Stick-shift or automatic? Factory seats kinda suck but truck itself rides quite nice, put in some nicer seats (later model ones should be a direct bolt-in) and you'll be nice and comfy on longer drives.
 

jdog1

New member
yup 2500 series.probably the most gutless 350 Ive ever driven. but for now it gets me to school and back. And its an automatic. As for the seats do you mean out a of a 2015 or a late 90s early 2000 truck?
 

Rot Box

Explorer
Most of my friends and family had this era of GM when I was growing up. Imo it's really tough to beat the TBI 350's. Although they aren't a powerhouse by todays standards they're stupid simple and very reliable. When it comes to the front end they eat the cheap lifetime warranty components like candy (pitman/idler ball joints etc) so use the good stuff even if it costs more. Hopefully you have the 4L80E trans as well they're very stout..

One of these would be towards to top of my to-do list: http://4x4posi-lok.com

Anyway those pickups work really well right out of the box. I would give it a good tuneup and build your platform then his the road/trail.

Andrew
 

jdog1

New member
OK, ill look into the posi lock thing. But before that I need a canopy so I can stay dry on trips.I also want to make the bed platform removable so I can still use it as a truck.so...Ive got a bit of work ahead of me.
 

underdrive

jackwagon
yup 2500 series.probably the most gutless 350 Ive ever driven. but for now it gets me to school and back. And its an automatic. As for the seats do you mean out a of a 2015 or a late 90s early 2000 truck?

As RotBox said, I sure hope you got the 4L80E trans, the lighter duty 4L60E is, well, lighter duty, and can be problematic sometimes. Decode the list of RPO codes on the sticker inside your glove box, it will tell you every single option your truck was equipped with when it left the factory.Also he is right on the Posi-lok, GM's electro-vacuum-mechanical front axle engagement system is about as stupid as one can conjure, so simplifying it would go a long ways towards reliability.

Seats, yes I meant late '90s and early 2000s. Super new is super expensive, also new cabs are designed very differently and tend to have lots more interior space so what fits just fine in a new regular cab may very well call for an extended cab in your body style (which you obviously don't have). So stick to newer than your model year and fancier in trim level, but still cab dimensions close to yours, and you should be alright.
 

jdog1

New member
cool, ill have to look into the trans. its probably got the 4l80e because it came from the factory with a towing package. but ill have to look into that just to be safe. as for the seats that will have to be sometime down the road because money inst nearly flowing out of my pockets right now and, id rather spend the money on a bed platform first.

edit: from what i found it does have the 4l80E. which is good. because im not experienced enough to tackle a tranny swap....
 
Last edited:

underdrive

jackwagon
You're all set then. I wouldn't have suggested a swap right away anyways, the 4L60E is a decent transmission, just not quite as strong and reliable as the bigger 4L80E is all.

Understood on the seats, it was more of an idea if you happen to run into a nice set for cheap on Craigslist or something. Definitely not a priority upgrade so long as your back doesn't tell you otherwise.
 

jdog1

New member
the seats aren't a priority right now. but, this weekend i plan on cleaning it up a bit by repainting the wheels. and if amazon cooperates i may get to install a new radio because the one in there died the day i got my truck.
 

underdrive

jackwagon
Tunes are important indeed!

What color are you painting the wheels, same silver as the center section of the truck sides? I see you already got the stainless trim rings and chrome center caps, so you're a step ahead there (IMHO steel wheels just don't look right without the trim rings and center caps).
 

jdog1

New member
so... the radio magically started working again.....right after I came home to the new radio I bought. anyways im just gonna paint the wheels silver for now. you cant tell from the picture but most of the paint has fallen off the other wheels. but i promise ill get some better photos up soon.
 

Kmehr

Adventurer
That's a fantastic truck. I've got an 89 1500 and its really hard to beat. I had a 98 2500 before that with he 6.5diesel. the TBI 350 isn't a powerhouse but it's dead nuts reliable is really hard to kill, I'd be hard pressed to replace it with anything. The best thing about those trucks is that they are probably the absolute cheapest vehicle you can find to maintain. GM was the master of parts interchange and they made about a zillion of those trucks. For example, the water pump gave up on mine last fall. $19.99 for a rebuilt one. $19.99!!!. Not to mention, if you do ever kill the motor, you can get a brand NEW long block from GM for $1700, and it's so simple you could swap it in a weekend. Fantastic trucks. Offroaddesign.com is a great source for offloading upgrades if you're into that.
 

jdog1

New member
so....i haven't posted in a while. but there is a good reason for that. I had an accident all most 2 months ago and Ive been fighting the other insurance company to admit fault ever since. BUT, they finally did and I was able to get the cash to got to the wrecking yard and pick some stuff, as well as get brand new stuff from LMC Truck. (which is really cool. If you haven't heard of them check them out!)(pics coming soon.)
 

noJeepshere

Adventurer
You have yourself there a gem of a truck, very nice score there. They are dependable and tough and good looking and surprisingly capable in stock form. The TBI 350 isn't a powerhouse (210 hp and 300 lb/ft torque) but they'll go, and go, and go... You also have the 4l80e automatic, which is a superb transmission, it was bolted to everything from your 350 to big blocks and the diesel in everything ranging up to school buses and medium duty commercial trucks. Good stuff.

The front axle is a 9.25 (ring gear diameter) ifs, which is fairly stout, but it's hampered by the aluminum case and chintzy center axle disconnect. The case you can do nothing about, but I recommend highly the 4x4posi lock, especially if you ever want to wheel in the snow or ford a river. GM used a thermal actuator that needs to get hot and expands and pushes a rod to engage the front axle, and if it gets cold (ie. a water crossing or cold weather) it just won't work. If you want to keep the dash uncluttered, you can upgrade to the mechanical actuator used in later gmt400 trucks.

Your transfer case is an NP241 with a 2.72 low range and is a very good case. Pull it apart someday and throw a rebuild kit (new chain, seals, bearings etc) and a case saver and you'll never need another. A case saver is needed because as the bearings inside begin to wear, they let the gears rub against the inside of the case and will eventually break through. It's not an expensive upgrade but worth it. If/when you do an axle swap, buy a slip yoke eliminator kit and you're good to go.

Your rear axle is one of two: a 14 bolt or a 14 bolt. One is smaller than the other. The smaller 14 bolt (number of bolts holding the cover on) is a 9.5 ring and pinion and will survive forever in stock form with an unmodified motor. It is a semi-floating design, meaning the axle shaft transfers power AND holds up the truck, as the bearings ride on the shaft. Its weakness is the c-clip design holding that shaft in. If that clip were to break or come loose you're in for a wild ride! (This is a very rare occurence though, so don't panic) The bigger 14 bolt is the Holy Grail of rear axles. It is pure beef. Bullet proof. Unbreakable. The last axle you'll ever need. It has a massive 10.5" ring gear and is a free floating design. That means the bearings have their own race and the axle shaft only has to transfer power, so that if you ever break a shaft, you'll be able to drive home no problem. This is the axle rock crawlers and mudders and guys that tow all want. If your glove box has "G80" as an option code, you have the gov-lok option, which is a good thing. The gov-lok often gets a bad rap for being either worthless or breaks easily, but that's the 10 bolt gov-lok. The 14 bolt (either axle) gov-lok is a different design and is pretty stout and reliable and is a real locker, not a limited slip like the 10 bolt unit. The way you can indentify which axle you have without pulling the diff cover is pulling a hubcap off. If there are bolts under the cap, you have the full float, if not, you have a semi.

Power upgrades for the 350: find some vortec heads, they flow better, allowing you to make more power across the band. You'll need a new intake to do that swap, but it would be worth the investment. Basically think of the motor as a big air pump, and the more efficiently you can move air, the more power you'll make. Just stay away from cheap stuff, like a $20 cold air intake kit. Just no. And when the time comes to do a rebuild or swap, GMPerformance has a 290hp crate motor that is drop in and only a few hundred more than a basic small block. Totally worth it. On my Yukon, when the time comes, I'm going to go with an HT383E motor, as 330 hp and 430 pounds of torque are hard to beat. It's pricey that's what you have to pay for awesome.

As for your seats, anything from an 88-98 truck or 93-99 suv will bolt right in with minimal modifications. That means you can put in electric leather buckets for relatively little dime. But a split leather bench with manual adjust would be the best way to go.

Upgrade your rear axle with a Detroit locker (if you don't have the gov-lok) and a set of disc brakes. Unless you have the semi-float axle, then find a full-float and put a Detroit and discs on it before you bolt it in.

That's the nice thing about GM trucks, parts interchangability is crazy! All the motors use the same frame mounts for the engine, all the bellhousings are the same, the transmission outputs are all the same, the rear axles all use the same spring pad/shock mounts so any axle from any truck will go in easily. And from the b-pillar forward, they're all the same sheet metal and frame.

I am actually a little envious of you and your truck, I almost bought one very much like your's years ago but my brother offered me the Yukon at a great price and I knew it's history. Happy motoring with your old Chevy! ahem, GMC...
 

stioc

Expedition Leader
^ wow, that's gold right there. I have never owned a GM truck nor thinking about it but once I started reading I couldn't stop.
 

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