Frame swap question

[dieselden]

This may be a dumb question, but I'm not sure myself. It's been over 20yrs since I did any work on one of these trucks

So I bought my 16yr old boy his first vehicle this year.
1981 GMC long box
He wants to start working on it this winter and was asking about switching to a shortbox.
I just found a 81 Chevy shortbox stepside frame.

Will everything from from the Gm swap over and fit the Chevy frame without any major mods? Will a fleetside fit on a stepside frame
I know I will need a box and driveshaft.

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[CSFJ]

Yep, you're good to go.

 

[1973c10]

Yep

 

[Charlie]

 

[shiftpro]

If it's the same shorty I'm looking at, in Calgary, then NO IT WON'T WORK!

Just kidding, barely.

FYI, it's easy to make a long wheelbase into a shorty, if it's a 4x4 and you want to lift it a little. You just move the rear spring perches forward, and toss the rear perch for a shackle flip. Then cut the rear portion of the frame off. Totally legal in Canada, err sorry, BC. I don;t know what the laws are in other provinces. In BC we can not do any welding on frames other than repairing broken shock mounts or welding behind the rear shackles, as in welding on a hitch to the frame.

 

[HotRodPC]

All a bolt on swap. Lots of work though. The bigger concern should be the legalities of the VIN swap. Frames are stamped with the last portion of the VIN. So what's going to happen in your province if the Cab VIN does NOT match the frame VIN? That's what I'd be most concerned about and how you're going to deal with it. Sometimes, just handle it and keep quiet is best but sometimes.... all depends on your local laws.

 

[shiftpro]

All a bolt on swap. Lots of work though. The bigger concern should be the legalities of the VIN swap. Frames are stamped with the last portion of the VIN. So what's going to happen in your province if the Cab VIN does NOT match the frame VIN? That's what I'd be most concerned about and how you're going to deal with it. Sometimes, just handle it and keep quiet is best but sometimes.... all depends on your local laws.

Good points but in reality it's pretty relaxed in BC at least, and I would think most of Canada including Ontario as much. The Black book value of these precious machines is just so low they just fly under the radar of most scrutiny.

 

[dieselden]

Not in Calgary.

I will have to look into the vin swap. Never thought of that.

Going to start a major overhaul on truck. So thought it would be a good time to swap to shortbox.

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[dieselden]

By the way, thanks for info.


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[75gmck25]

I believe that the one item that won't transfer over is the 20 gallon fuel tanks. Short box trucks only have space for a shorter 16 gallon tank.

The only drivetrain modification I can think of is to shorten the driveshaft. Since they are both '81 it may be fairly simple, but GM had a habit of using different driveshaft and u-joint setups based on transmission, GVW and axlel, so it would be best to verify that you get one that works. The other option is to have a shop shorten the driveshaft.

Bruce

 

[HotRodPC]

I believe that the one item that won't transfer over is the 20 gallon fuel tanks. Short box trucks only have space for a shorter 16 gallon tank.

The only drivetrain modification I can think of is to shorten the driveshaft. Since they are both '81 it may be fairly simple, but GM had a habit of using different driveshaft and u-joint setups based on transmission, GVW and axlel, so it would be best to verify that you get one that works. The other option is to have a shop shorten the driveshaft.

Bruce

True True !!! Long Beds got either 16 or 20, Short Beds got 16 only due to the front leaf spring hangers being in the way of 20 gal tanks.

 

[dieselden]

One good thing about this shortbox frame.
It still has fuel tanks on it.
Still debating on either 350 or ls for it. So there will be driveshaft replacement anyway

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[HotRodPC]

If money and time aren't an option, I don't think there's any debating that. LS or nothing is the way to go. Only thing to debate there is, Drive by Wire, or Drive by cable.

 

[Frankenchevy]

All depends on what you’re into. I’m not an ls fan based on it not looking like a classic sbc. I like something to look like a sbc. Money/time don’t really matter to me. Then again, opinions are like you know whats...

LS swaps are nice if pulled off well, too.

Do what makes you happy. I didn’t get into this truck because it out performs other trucks. For me it’s aesthetics. Other’s reasons will vary.