K20 and Sierra 2500 Differences

[Sarge261]

Hey all,

I am beginning the tear down of the donor truck for my project and I have a few questions.

The donor truck is a 86 GMC Sierra 2500 4x4. My truck is a 85 Chevy K20. Are there any differences in the frame? I am running a plow on my truck and will bring it over to the new truck, this is why I ask.

What does the High Sierra Package consist of?

The spec sheet in the glove box says its a wide side, I have a regular 8' box for it, will I have a fitment issue with the box?

Are there any other significant changes between 85-86 model year and between Chevy and GMC?

I am probably going to go with a Painless harness for the dash and the engine compartment, as the ones in either truck are pretty trashed. Has anyone used painless and if so was it a nice quality part with good fitment.

I was also thinking about putting in a 700r4 in place of the old 400 3 speed, good move or not? This truck will be used mostly for plowing and as my shop truck but I will drive it and the 4.10's combined with the 3 speed = screaming at 45mph so I thought I may change it.

So far this build is going well, all the bolts have come out and I have the cab almost ready to remove from the frame.

Thanks for all the help,

Sarge

[rare86]

Theres very little difference between the two. Mostly just trim packages. I dont think the 700 would hold up as well as the 400 in stock form. As for running the 4.10, go to a 33 in or larger tire, and enjoy.
Beds are not different, wide side is just what they called the fleetside trucks

[Sarge261]

Thanks much for the info. I am pretty sure that the tranny I have has a shift kit in it too which is a bonus. I was just wondering about the 4 speed, but I guess I will keep what I have and put the money twards a new carb and a electric fuel pump.

Thanks

Sarge