While the 700-R4 is even longer than a TH400, the easy-to-retrofit 200-4R has the same overall length as a TH350. Most TH200-4R cases have a compositebolt pattern, so they can be bolted directly ...

All TH-200 and TH-350 and most Powerglide transmissions have 27-spline output shafts. Powerglide cases come with only the Chevy block-mounting bolt pattern.