[Don Whitmore]

A powerglide versus turbo 3-spd difference is not that easy to figure out. A pure back-to-back swap won't give you correct answer. You need to optimize each setup i.e., cam, gear, tires etc.

That said, I would guess an optimized turbo 3-spd would be better due to less converter slippage and ability of trans to keep engine in a more narrow power range. There are some on this board who have good knowledge of converter efficiency, would like to hear their input...