Frame swap question

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

dieselden

Junior Member
Joined
Apr 11, 2018
Posts
4
Reaction score
2
Location
CANADA
First Name
Dennis
Truck Year
81
Truck Model
C10
Engine Size
350
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.

Sent from my SM-T810 using Tapatalk
 

CSFJ

-----------------
Supporting Member
Joined
Jul 1, 2014
Posts
6,160
Reaction score
5,162
Location
------
First Name
-------------
Truck Year
-------
Truck Model
-------
Engine Size
-------
Yep, you're good to go.
 

1973c10

Full Access Member
Joined
Sep 25, 2015
Posts
6,376
Reaction score
24,013
Location
Oregon
First Name
Don
Truck Year
1973
Truck Model
C10
Engine Size
454
Yep
 

Charlie

Mopar by Birth. Chevy by Choice.
Joined
Aug 2, 2017
Posts
1,837
Reaction score
909
Location
Euless, Texas
First Name
Don
Truck Year
1974
Truck Model
Cheyenne 10 LWB
Engine Size
350/TH350/AC/4 BBL Quadrajet
:welcome:
 

shiftpro

Full Access Member
Joined
Aug 31, 2012
Posts
4,855
Reaction score
6,085
Location
BC Canada
First Name
shiftpro
Truck Year
73-87
Truck Model
1500, 2500, 3500
Engine Size
350, 383, 454, 496!
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

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,008
Reaction score
8,977
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
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

Full Access Member
Joined
Aug 31, 2012
Posts
4,855
Reaction score
6,085
Location
BC Canada
First Name
shiftpro
Truck Year
73-87
Truck Model
1500, 2500, 3500
Engine Size
350, 383, 454, 496!
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

Junior Member
Joined
Apr 11, 2018
Posts
4
Reaction score
2
Location
CANADA
First Name
Dennis
Truck Year
81
Truck Model
C10
Engine Size
350
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.

Sent from my SM-T810 using Tapatalk
 

dieselden

Junior Member
Joined
Apr 11, 2018
Posts
4
Reaction score
2
Location
CANADA
First Name
Dennis
Truck Year
81
Truck Model
C10
Engine Size
350
By the way, thanks for info.


Sent from my SM-T810 using Tapatalk
 

75gmck25

Full Access Member
Joined
Oct 13, 2016
Posts
2,018
Reaction score
1,811
Location
Northern Virginia
First Name
Bruce
Truck Year
1975
Truck Model
K25 Camper Special TH350 NP203
Engine Size
5.7
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

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,008
Reaction score
8,977
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
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

Junior Member
Joined
Apr 11, 2018
Posts
4
Reaction score
2
Location
CANADA
First Name
Dennis
Truck Year
81
Truck Model
C10
Engine Size
350
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

Sent from my SM-T810 using Tapatalk
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,008
Reaction score
8,977
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
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

Proverbs 16:18
Joined
Jan 3, 2018
Posts
5,905
Reaction score
7,250
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
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.
 

Forum statistics

Threads
41,856
Posts
903,618
Members
33,369
Latest member
mitchell1128
Top