I just put a 6.2 out of a escalade in a 1980 suburban with a th400. I had Speartech make me a standalone harness for the engine. Got it all in and went to fire it up after changing everything in the pcm to run it and no luck. Called around and talked to Speartech and they said I needed HP Tuners that EFI couldnt make it work. Well after a day of trying I ended up getting HP Tuners just to disable VATS and what you know, it fired right up. I was told that I was the 3rd person to call about this when I was calling around trying to figure this out.

It really sucked to use a $99 credit just to disable VATS since I have unlimited E38 in EFI.