Looking at a 80 that has 124k miles, 1991....guy said he put $5000 into it and has proof, rebuilt front axel, looks clean clean. Second owner. OME susp. few minor issues. Would you pay $8000?
Not for a '91. No OBDII, no factory lockers, older transmission. The prices of these things are going crazy lately but a vehicle is worth what someone is willing to pay.
3FE dog engine too in the '91 IIRC. Sounds like seller is wanting 100% of what he put into the truck out of it and that's unrealistic. Mileage is certainly good. Where has the truck lived? Rust belt or bliss of arid desert? $3-4K at BEST maybe, but that's up to you as the buyer.
Yes assuming the didn't have $5k into it and it had a $3K asking price instead, that's still on the high side for most '91s. The low mileage is good and might make it worth a $3k asking price, but I would think on the high end of things (depending on what the extra $5k went to) that $5500 would be more realistic.