What applications use SB 727's?

A lot will depend on year and what it's going in. They made small block 727's starting in '62 all the way up to the electronic versions in the late 80's. The '62-65 versions have a bolt on flange in the rear....the later ones are slip yoke. '62-8 have a single wire neutral safety switch....the '69-up are 3 wire (the switch doesn't just swap over!) The pumps and converters changed in '68 also. Trucks and Vans have their own version called a Loadflite. Most will interchange with a car if they're the slip yoke type. There are some internal and external differences so get year/make/model off whatever donor you use so you can order the correct parts for it. There is also a number on the pan rail to verify what the trans was in originally.