I have a 1984 s-10 Blazer that has a great body, but a worn out 2.8 V6. I purchased a 1991 s-10 Blazer with a 4.3 engine that has very low miles. What I would like to do, and theseare my questions.........
How difficult will it be to change the wiring harness from the 91 over to the 84?
Besides changing the fuel tanks, are there other pieces I'll need to make sure I take off the donor?
Is it that difficult to take the entire wiring harness and swap it over?

 

You would need the transmission from the donor truck as well. The 2.8L v6 does not have the same transmission bell housing bolt pattern that the 4.3L v6 has.

As far as wiring change over... It may require both the engine and interior harnesses, but you would have to get wiring diagrams for both trucks to determine what the differences are. The biggest problem (wiring & controls wise) is you are going to be going from a carb'd motor to a TBI motor...

 

I'm changing the transfer case, transmission, and engine from the 91. According to the manual the engine and dash harnesses are totally different. I think I'm going to wind up taking the dash from the 91 as well. I guess I'll find out how much difference there is between the sheetmetal on an 84 and a 91 inside the cab.
Thank you for the reply