Looking like a strong possibility that I am going to go with a 5.3 LS engine and 4L60E transmission from a 2004 Silverado 2WD. Assuming I can get the engine, transmission, ECU, transmission controller, and all the related wiring harness everything should talk to each other just fine. The 4L60E has a lower numerical final ratio in overdrive so depending on tire size selected I can probably run the original 4.57 rear axle and have reasonable engine RPM at 55/60 mph.
