727 -> 904
I switched years ago from a 904 to a 727 because I was told the 904 wouldn't take the abuse. The 904 leaked a lot, so I needed to rebuild a tranny anyhow. So I went with the 727. The car went from being able to do burnouts with my stock little 318 and 2.76 gears, to not being able to get out of it's own way. Now, I'm putting that same 727 back in the car in a couple of weeks after I finish my engine (since it only has about 1K miles on it), but you can bet when I get the extra cash to rebuild the 904, it's going in the car ASAP.