As with any EFI conversion, the real skill involves wiring the harness, sensors, and the computer. It's definitely a job best left to experts such as those at Hi-Tech. Here's how the harness arrived with the GM 4.3L and the TH700-R4. According to Morse and Ken Carner, the basic challenge is to make the Vortec's computer think it's still in the original GM donor. When completed, the engine/computer/sensor array is stock GM. Diagnostics and service are the same as on the original donor.