I've been trying to decide what drive-train to install into my '52 3600. I'm planning to stay with the straight axle and add power steering and disc brakes. It seems that the 6 cylinder will allow the most room for the steering shaft etc. But I have just found an '89 TransAm GTA 350 MPFI engine and 700R4 trans complete with the computer for $500.00. I'm really tempted. Since I want to build a working dually truck that engine/tranny should have enough "grunt". Would anybody like to speculate on fuel economy with that setup and 3.73 gears?