Seats

[GMC-FAN]

Not sure if this has been asked before… But will a early 88-98 bench seat fit in a 81 square? I came across a nice bench out of a 92 and was wondering how much modifications would be needed to swap them. Thanks!

 

[AuroraGirl]

Not sure if this has been asked before… But will a early 88-98 bench seat fit in a 81 square? I came across a nice bench out of a 92 and was wondering how much modifications would be needed to swap them. Thanks!

I would imagine the rails prob sit slightly different spot and maybe a different height but it’s a simple mechanical device that you can prob easy swap. No idea side to side. I’d say prob not if it was a split bench like my dads 96.

 

[GMC-FAN]

Yeah, just seeing if anyone has done it on here, it’s a solid bench, I’m kind of a large framed individual and was looking to move myself back a little, and maybe down a bit. I’ll take some measurements and pull the old seat out and see what I come up with. Thanks!!

 

[bucket]

I've seen trucks with the '88-'94 seat swapped in and it fits. I would guess that they bolted the newer seat to the original tracks, but I do not know that for certain.

 

[yevgenievich]

For trucks and suburban either use original brackets and modify them to fit gmt400 seat or reshape the floors. Also can modify the gmt400 brackets I believe. On a k5 should fit with just drilling new holes

 

[Lowered87]

Not sure if this has been asked before… But will a early 88-98 bench seat fit in a 81 square? I came across a nice bench out of a 92 and was wondering how much modifications would be needed to swap them. Thanks!

The way I did the swap without modifying anything was I made a template from 1/4 inch plywood and some 1 by 4 boards. I used the old bench seat rails and the new seat with the newer rails totally removed. I cut the plywood and mounted it to both seats being careful to cut the plywood exactly at the edges of the seat for the rear and sides. I bolted the old seat supports into the truck and then took the template off of the old seat and bolted it to the seat supports as the bolt patterns should match. Once bolted, you have a piece of plywood that represents the footprint of the old seat width wise and rear. Slide the rails back and forth to ensure no interference. Next remove the plywood from the newer seat. You will have to use the 1 by 4 cut to fit in the indent in the bottom of the seat. The 1 by 4 is bolted to the seat and the plywood is cut to the size of the seat. Leave the plywood screwed to the wood rails and unbolt from the newer seat. Make sure to mark on the plywood front, rear and top. at the rear top of the new seat template mark a centerline. Take the newer seat template and lay it onto of the old seat template which is bolted in the truck. Space the templates apart with 1 by 4. Line up the rear and centerline. Once lined up, screw the newer seat template to the older seat template. Unbolt and then drill the holes fro the new seat template through to the older seat template. Take apart the templates and use the bottom that has all the holes. Use that piece of plywood to cut 2 pieces of aluminum plate and a piece of aluminum square. What is created is a small strip of aluminum plate that becomes your adapter from old seat to new seat. It is so exact that your new seat will look factory as it will not hit the rear window and it will flip forward perfectly. From there you can make slight modifications if you wish to tip or lower. The main thing is you have correctly located the seat.

Not saying it is the correct method but it allowed me to install the seat without guessing.

Other option is to 3D scan everything and mock it up in cad. Much more expensive. If my above description is confusing then ask questions and I will try to assist.

 

[Raider L]

Remember the cabs are the same from '73 to '86 because the cabs were changed to the new truck in '87. But did the interior dimensions change? I don't know. Has anyone seen a big change in interiors in '87 to '90whatever? Width, height, depth to the steering wheel at least? I would think they would have been very close except like is being discussed about the holes in the floor. My question is why would the engineers change the holes in the floor if the seat dimensions are the same? What changed, the shape of the floor under the seat? Why?

 

[bucket]

Remember the cabs are the same from '73 to '86 because the cabs were changed to the new truck in '87. But did the interior dimensions change? I don't know. Has anyone seen a big change in interiors in '87 to '90whatever? Width, height, depth to the steering wheel at least? I would think they would have been very close except like is being discussed about the holes in the floor. My question is why would the engineers change the holes in the floor if the seat dimensions are the same? What changed, the shape of the floor under the seat? Why?

The newer trucks have a nearly flat cab floor. No giant humps to clear the saddle tanks.

This is a floor from a newer truck:

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[mrghostwalker]

I had an 88 put into my 83 until I re-build the correct seat. New holes had to be drilled in the floor as the bolts did not line up with the original mounting points. Once it's in it looks and works just fine.

 

[Raider L]

@bucket,

Wow, that's a lot different from my floor. Mine has that cavity under the seat, and that big step up to a ledge near the wall, like a shelf? Huh. That would be a much easier floor to deal with than mine would be.

 

[Raider L]

@GMC-FAN,

How are you going to deal with the nuts being welded under the floor? Just drilling new holes, are you going to get someone to help with putting a nut under the floor while you turn the bolt up top? I never have anyone to help me do anything so I always have to figure out how to do it by myself. I'd end up modifying the seat rails so it would line up with the original holes, somehow. Just make sure you put a large body washer under the nut underneath the floor to spread the load out. Otherwise if you had an accident the seat bolt might tear through the floor sheet metal and the seat would come loose inside.

 

[Lowered87]

@GMC-FAN,

How are you going to deal with the nuts being welded under the floor? Just drilling new holes, are you going to get someone to help with putting a nut under the floor while you turn the bolt up top? I never have anyone to help me do anything so I always have to figure out how to do it by myself. I'd end up modifying the seat rails so it would line up with the original holes, somehow. Just make sure you put a large body washer under the nut underneath the floor to spread the load out. Otherwise if you had an accident the seat bolt might tear through the floor sheet metal and the seat would come loose inside.

Look into rivet nuts. You can drill the hole and rivet the nut flush inside the cab. You have to be careful to purchase the rivet nut so it has a crimp range for the thickness of steel of the cab floor. I put rivet nuts in whenever I can.

 

[Lowered87]

Remember the cabs are the same from '73 to '86 because the cabs were changed to the new truck in '87. But did the interior dimensions change? I don't know. Has anyone seen a big change in interiors in '87 to '90whatever? Width, height, depth to the steering wheel at least? I would think they would have been very close except like is being discussed about the holes in the floor. My question is why would the engineers change the holes in the floor if the seat dimensions are the same? What changed, the shape of the floor under the seat? Why?

A regular cab is still a squarebody including 1987 (R10/V10). The crewcabs and suburbans went until 1991.