pontiac uses the st300, which i think is the same as what olds referred to as the Jetaway
both are 2 spds, and similar if not identical gear ratios. but jetaway sounds so much cooler than slipnslide... er.. powerglide.
2spds are good for high torque motors with or without low (numerically high) rear gears, whether in racing drag or autox. they can keep you in your desired torque range. their first gear is similar to second gear in most other automatics. i have a little bitty engine, so my 2 spd is gone. i need all the gear i can give it to keep up with a v8. i think i'll tend to see ford headlights and pontiac taillights once i'm back on the road 1st gear wont last to 30mph w/ my combo.