They will physically fit, but you need the brackets. The consoles mount to stamped steel slot brackets and you would need to weld or attached them first.
Yes I did the same to my 86 Suburban, the steel bracket has to be attached to the roof support bars and you will have to drill a few holes in the roof support bars to be able to attach it (or weld it). Also the front has a cut out where it slides in, but you can just drill a couple extra holes and use screw to make it work.
The 89 to 91 model years already have these holes pre drilled even if your suburban did not originally came with a roof console, so that is why they only sell them for these years.
They can be mounted in any 73 to 91 suburban however, with the above mentioned modifications.
