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View Full Version : Converting an '89 Silverado


Gus
08-19-2004, 05:18 PM
My brother wants to know how easy it is to take the under body of an '81 to '87 Chevy 1 ton (frame, axles, transfer case, axles, tranny, well everything but the body) and put an '88 to '89 body on it. Will there be any length issues being he wants a supercab shortbox for the body and a singlecab longbox for the '81 to '87 frame. Just any info would help greatly. (I say he should go Ford)

FU Toolbag
08-19-2004, 06:09 PM
the step in the frame will mess you up

OKOR[f]
not all men are pigs
some men are gay

boyzen
08-19-2004, 06:40 PM
go ford....

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Gus
08-20-2004, 03:24 PM
Dude, whats this step in the frame your talkin about, I ain't familiar with chevy frames, err, a well chevy anything really. (I just pull them off da trail, don't fix em)

FU Toolbag
08-20-2004, 03:52 PM
The frame is lower under the cab and then steps up for the box. It's not the year change, it's the cab change. Just crawl around under and bring a tape and pencil. Better yet, put both side by side and roll between them.

OKOR[f]
not all men are pigs
some men are gay

Gus
08-20-2004, 04:50 PM
ok, maby we can work around this step thing, but what about the length? He seems to only want the solid axles, carburated motor, well he justs wants to steer clear of the computer controlled anything. I think he should just get a chassis and frame of the newer model, then pick up the motor, trans, t-case, axles and do a solid axle swap, but he thinks it'll be cheaper his way. (lets be truthful, go ford)

u2slow
08-20-2004, 07:25 PM
The 73-87 reg. cab longbox wheelbase is 131.5"

The 88-98 xcab shortbox wheelbase is 141".

The kick in the frame will be the clincher. The low spot on the frame for the cab won't be long enough on the old frame to fit the newer xcab. You can raise the whole thing up to clear, but that could mean a 4" body lift under the rest of the cab & box to level it all out. This is also the only way I can see keeping the stock saddle tanks from the old frame. The old frame is also narrower, so you'd have to see if the newer 26-gallon inboard tank will fit, or see if you can mount a Blazer tank at the back.

Maybe you can hack out the rear floor on the xcab and re-fab it so its higher up.

Suburban frame has a longer low section, but you won't be able to push the axle back 10" without losing that big 40-gallon fuel tank. Crewcab frame also has enough of the low section - maybe that's the way to go, and cut it down some.

IMO, find a cheap 88-98 xcab shortbox and do the SAS swap.

FU Toolbag
08-20-2004, 09:06 PM
The easiest way is the sas on the newer truck. The speedo and the other cab electrics will be a pain to rework to go with a different frame/drivtrain setup. If you want to use the excab on a burban frame you could shorten the box to fit the wheelbase of the burb. Basicly, how tallented is this guy? If he's creative and capable, than he would probably enjoy doing the mix and match thing. If not, start with doing a sas, and learn from there. Where are you? I have a 86 and a 94 crewcab frame here if you are in the okanagan you could pop by and do some measuring. No cabs, but can compare them in their nakedness.

OKOR[f]
not all men are pigs
some men are gay

Gus
08-22-2004, 07:39 AM
so what if i just put the axels motor tranny an transfer case on the 89 frame, wouldnt that work?, and just put the 89 driveshaft on it?

FU Toolbag
08-22-2004, 01:16 PM
Yes it would work, but your probably going to need different drivshaft lengths, maybee. Why not leave the newer engine, tranny ext and just do the sas?

OKOR[f]
not all men are pigs
some men are gay

Gus
08-22-2004, 02:08 PM
cuz computers suck balls

u2slow
08-22-2004, 04:49 PM
quote:Originally posted by Gus

so what if i just put the axels motor tranny an transfer case on the 89 frame, wouldnt that work?, and just put the 89 driveshaft on it?

I like that compromise... not too much fabbing. Then you're actually starting with a whole truck rather than a cluster-fuck of parts.

Aside from the SAS, just make new crossmember. I believe all the trans/t-case lengths were the same from 81 until 90. Driveshaft might just fit - until you lift it [4]