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Will bolt on trans tunnel cover fit a 91 4x4 burb?

M

mpascino

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Hey guys, been a while but I'm getting some time to work on projects a little more lately.... Does anyone know if the older type of bolt on trans tunnel cover is the same shape as the "newer" floor pans? What was the last year of the bolt on cover? Does anyone happen to have one they want to sell? Was the bolt in tunnel still in production when they started the using the np208 with the t-case shifter mounted on the body? Not the end of the world but if there is one out there it would make life easy.
I recently swapped an SM465 in the '91 diesel burb and unfortunatly it needs to come out again....Started making noise, gonna have to go through it. Between the 3.5" exhaust from the turbo and fact that I can barely tilt the engine down without having to disconnect a bunch of other junk from the engine, I thought it may be easier to cut out half the floor so I can slide the trans back. :D Hmm, maybe I should find an assitant this time rather than playing russian roulette with a 200 lbs paper weight.....
 
I got some pics on my hard drive which shows the difference between the 80 down and 81 up bolt on trans tunnel. If somebody tells me how to upload the pics into the members’ gallery, I show them to you.
 
Here's a 78 tunnel
and my 91 tunnel.

I believe the bolt-on tunnel stopped around 82-83. Are you sure the older tunnel won't work? The NP203 had a floor mounted shifter also.
 
I looked closely at mine recently, (1986 body) and it looks like you can "just" drill the spot welds out for the tunnel, use those nuts that clip onto the metal, and put an older tunnel in.

It's not going to be a clean install if that matters, and getting at the spot welds under the dash will probably be a big hassle as well.
 
No because the older tunnel is shorter. If anything, you modify the early model cab to the later tunnel. Count the bolts between the two and the later model tunnel has two extra bolt holes.
 
u2slow said:
Here's a 78 tunnel
and my 91 tunnel.

I believe the bolt-on tunnel stopped around 82-83. Are you sure the older tunnel won't work? The NP203 had a floor mounted shifter also.
Click to expand...

Hmm, that is strange. Your late model 4wd tunnel isn't a bolt-on tunnel. My brother picked up a bolt-on tunnel for an 84, and I have an 89 blazer body with a bolt on tunnel.

I need to resize that pic I have so I can show you.
 
Hmm, that is strange.
Click to expand...

You're telling me! :confused: I haven't seen a single removeable tunnel since the early 80's - just two very distinct floor stampings... a high hump and a low hump.

203 was tcase shiffter
Click to expand...

You're right! I remembered it was a linkage type shifter but forgot it mounted to the t-case :o
 
I mostly have experience with the older stuff. Of the little newer stuff I worked with, I only seen the bolt on trans tunnel.

BTW, is your pic of your early model trans tunnel from a 2WD 4 speed? The tunnel dips lower in back than the tunnels I've seen.
 
Okay, I've two pics in my gallery. Can somebody tell how can post them here?
Aww, Screw it, I just link it instead. Link One and Link Two with the later tunnel in a 2WD cab
 
Last edited:
u2slow said:
Here's a 78 tunnel
and my 91 tunnel.

I believe the bolt-on tunnel stopped around 82-83. Are you sure the older tunnel won't work? The NP203 had a floor mounted shifter also.
Click to expand...

I have my other 83 tore down , and it does have a bolt on tunnel , looked under my Tan 83 and same there . I looked at Shawns 86 in the front yard and it is welded in .

However on that 86 it IS definitely a seperate piece WELDED on to the opening in the floor , the spots where the bolt holes would be have little dimples kinda look like spot welds .

So I don't know the cutoff date . We need pics from 84 and 85 too :k5: :k5:
 
My '87 with 700R4/208 has the welded-in "bolt-on" looking trans tunnel. I'll take a pic if anyone would like to see.
Since I'll be doing so much other sheetmetal work anyway, I'm considering making it a true bolt-on.
 
Well, you learn something new every day. It seems there where a lot of trucks from the eighties on up that came with a solid trans tunnel. If you have solid trans trans tunnel, than you can convert to an early model bolt on tunnel. The tunnel appears to be the same shape. The later model bolt-on tunnels are longer, so one of those would be better choice cover for what you want to do in my humble opinion.
 
Thanks for the info guys. I think it is in my best interest to find a later model bolt in tunnel... I wonder if I can drill the welds out of the original without ruinning it. I may just start looking around for one in the mean time. Some one has to have one somewhere...

Mike
 
If you ask me the difference is in the rear floor change, not the "typical" '80-81 body change differences. It's pretty obvious from your pictures that the early floor is much different, because the "bed" extends much further forward. (which we all know)

So I *suspect* all the tranny tunnels after the rear floor change are interchangeable. I've never had a 2wd and 4wd bolt in tunnel next to each other, although I keep hearing they are different, according to the GM parts manual, the floors are the same for all K5's '85-88.
 
I should point out that green '78 tunnel was from a regular cab pickup, and the red '91 tunnel is my crewcab. It seems like most of the info posted is K5 specific. I guess the question now is which tunnel best fits a Suburban?
 
Not really helping your suburban question, but that '78 tunnel doesn't even look like 4wd could be made to fit with it. Where would the shifter go? The distance for the t-case shifter is going to be IDENTICAL with the same drivetrain regardless of year. (maybe the difference on the later figure 8/round pattern 465/205 since the length of the adapter changed 3") Compare that '91 picture with the '78 and you'll see. Even with the link 1 pic above compared to that '78, looks like a 2WD vs. 4wd difference only, at least for that type of floor.

I already made it clear I don't have much first hand experience with this older stuff, but I just don't see ANY tranny/t-case setup being short enough to get a shifter behind that '78 tranny shifter (cutout) on that picture you posted. Looks obvious to me the 465 shifter hole is in the same location for both years you posted pics to. The later shifter boot is just huge by comparison.

The differences in floor between Suburban and K5 are known, even under the drivers and passengers seats, but how far back does the tranny tunnel "hump" extend on a Suburban? IIRC on my '86 K5 body (not home to look) the tranny "hump" actually "extends" underneath the bed, (the vertical part where the bed meets the floor has a hump in it to accomodate the tunnel, even the piece that holds the carpet reflects this hump) while the picture link posted above (link 1) pretty much shows that the bolt in tunnel *is* the tranny hump in the older style floor pan, at least for K5's.
 
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