Here is what I did and this was 100,000 miles ago and no issues at all.

I purchased a used 2005 6.0 with 10,000 miles from a 2500 and swapped into my 1994 Z-71.

6.0 is easier (IMO) because it will bolt to 4L60 Tq converter with a little grinding on bolt holes in flywheel.

I used 1" off set engine mount adapter (I think 1") so the transmission and 4WD transfer case are in stock position. I took my ECM and harness to Nelson Performance and he handed me back a harness ready to plug and play. He even modified everything for the 4L60 tranny since the original harness was set up for the 2500 4L80 tranny. I purchased the Novak AC compressor bracket and it has worked perfectly.

My only goal for this swap was better drivability, better MPG and a lil more HP.

I have driven over 100,000 miles on this engine, have an additional 100+ HP, get 15 MPG in city and 18 Highway. Doesn't use a drop of oil, sounds awesome, and did I mention an additional 100+ HP???

The vehicle has 360,000 miles on it and I will be driving this truck and engine for easily another 10 years.


Just my 2 cents...