The 200-4r's were offered in lots of GM mid-sized cars, while the 700r4 was usually found in the 3rd gen Camaros and Firebirds. A 200-4r can be rebuilt to handle some serious horsepower. There are plenty of them now available that will handle 450 hp and up. I like the 200-4r swap over the 700r4 swap because the driveshaft doesn't have to be shortened and because you can adapt the t-400 crossmember. Parts you'll need to put a 200-4r in a first gen Camaro/Firebird: 200-4r trans, 200-4r locking torque converter + 3 metric bolts, 200-4r dipstick and tube, speedo gears, floor shifter conversion kit and lens (so you can grab all four gears), gear lever (mounts on trans), trans bracket (mounts on trans), carb bracket, lock-up kit, and modified crossmember. I have been informed that the t-400 crossmember does not exactly work without modification because the t-400's were used in big block cars, and big block cars used a different motor mount on the left (to clear the steering column), and that using an unmodified t-400 crossmember will 'tweak' the whole setup. The solution is to cut the tongue off the t-400 crossmember and then remount it in the proper place, or buy an aftermarket crossmember made for this conversion. I have read some poor reviews on some of these aftermarket crossmembers from people who have purchased them. Comments like, 'poor fit' and 'poor paint'. Plus, they're not inexpensive. While not required, you might need to change your rear end gearing. The 200-4r has a .67 overdrive. So if you're running 3.08 gears, that'll drop you to 2.20:1 or so. Which might be too low for your engine to make usable power. ..... You might check out http://www.camaros.net/forums/
for more information on this exact topic.