wiring harness differences
 

I am planning on swapping out the 1995 4.3 in wife's Jimmy for a 2000 4.3. The 2000 comes with everything except the heads which I plan to use off the '95 cause of the bolt pattern of the '95 intake manifold, which I'll also use. One option is to drill out and tap new bolt holes in old heads to match the 2000 intake manifold. Question is, what difference am I going to see in the wiring harness if I keep the original computer or use the 2000 computer.

you will probably see a difference since 96 and newer have a CSEFI while the 95 has CMFI which are operated differently there is going to be more wires on the harness

I would not recommend using the 2000 stuff in the '95. There are a lot of other things that the PCM from the 2000 will be looking for that your truck will not have or at least would not be compatible with the 2000 PCM like the original components (ABS, SRS, BCM, etc).

It will be, by far, easier to use the older top end (heads, intake, injection, distributor, etc).

Thanks for the advice guys, I'll post again if I buy and install the 2000 short block only. I don't need all the wiring problems.