Engine swap.

[Gman1776]

I've got a 2001 Yukon SLT 5.3L Vortex, to my understanding would a 5.3 LS gen III drop right in?

 

[strutaeng]

Yes, pretty much anything from a full sized vehicle will swap. The L59 starting in like 2002 was the flex fuel version of the LM7. It will run, but a little rich due to higher flow injectors (about 12% LTFT), but still within control of the ECU. You can just swap intake/injectors to avoid this. Still a good swap candidate.

DBW throttle body may be another thing to look for, as well as the earlier LM7s that had EGR. At some point that went away.