‘94 5.7 to ‘93 454 Conversion

[fancyTBI]

Donee: ‘94 K2500 5.7/4L80e 8 lug
Donor: ‘93 K2500 454/4L80e 8 lug

The basics:

I am looking at getting a running/“driving” ‘93 K2500 for the drive train. I want to swap the 454 over to my ‘94. Since I will have the whole truck to use as a donor, I’m not too worried about sourcing those hard to find parts. The ‘93 body is pretty ragged, the front end is wore out, and it has no brakes. I will salvage every good part off of it, scrap the cab, turn the back half into a truck bed trailer.

Questions/Concerns:

Are the ‘93 and ‘94 wiring harnesses significantly different? I assume I will have to swap over the engine harness at a minimum.

Are the computers different between the two years? I couldn’t find an exact answer.

Non engine related, are the torsion bars the same?

Please feel free to add any other insights. I want to swap it to a 454 so I can keep my ‘92 350 donor on the road.

 

[Schurkey]

Does the '93 7.4L use the high-pressure TBI fuel system? I don't remember when that started.

I'd expect stiffer torsion bars on a big-block vehicle, but measure the diameter on 'em to be sure.

Gear ratios the same? Maybe swap rear axles, too. Kinda suspecting that the 5.7L has a 9.5" rear axle, and the 7.4L has a 10.5" rear axle; and perhaps bigger brakes.

 

[fancyTBI]

Does the '93 7.4L use the high-pressure TBI fuel system? I don't remember when that started.

Good call. I’ll have to research that.

I'd expect stiffer torsion bars on a big-block vehicle, but measure the diameter on 'em to be sure.

my thought as well. Will put a micrometer on them both.

Gear ratios the same? Maybe swap rear axles, too. Kinda suspecting that the 5.7L has a 9.5" rear axle, and the 7.4L has a 10.5" rear axle; and perhaps bigger brakes.

I believe the ratios are the same. I am planning on swapping over the FF from the donor if it has one. I’m going to look at it on Sunday. Will try to get the RPO codes if they are readable and the VIN for sure.

Appreciate your input.