im starting to look for my transmission for my bird and was wondering how you identify all the different types of transmissions. (2004r, 700r4, th350, th400, 4l80 primarily) im used to mopar and having 2 choices for transmissions and all this different chevy stuff to do 1 job is confusing the hell out of me.

Experience. They all look different and they all use different oil pans. You learn what they are just by looking at them.

700R-4 has a square pan, 200-4R has no removable tailshaft housing,and the longest pan, usually stamped with "METRIC", TH350 pan is square but one corner kind of cut off, so it has 5 sides, while the TH400 has the most convoluted pan shape and a larger output shaft, as the 200, 350 and 700 all use a 27 spline output shaft.

Make sure you get a trans from a 3rd gen F-body or you will have to run a different crossmember that allows you to mount the torque arm to the crossmember instead of the trailshaft housing. The 4L80E, 4L60E, and 4L65E are all electronically controlled and unless you want to run a stand alone trans controller I would stay away from them. The stand alone controllers are pricey.

I'd stay with a 700R4 as it's a bolt in for your car. They can be built to take 575HP pretty easily. Unless you're making power in excess of 700 the TH400 is a horsepower waster. They suck up 25% of the engine's power just turning the guts. That turns a 400HP motor into a 300HP motor. The TH350's a good trans but was never offered in a 3rd gen so you'll have to spend $370+shipping on a new torque arm and crossmember to make it work, and the driveshaft will be too short, so you'll need a new one of those too. You're in the same boat with the 2004R, though it is inhernetly as better trans than the 700R4, for lower power levels it isn't worth the swap hassle. The 700R4 bolts right in, has OD, and can take some serious power when built right. That's how I'd go.