If you're going with the large (4½") bolt pattern, just get a complete drum setup off virtually any 5 x 4½" RWD/4WD up until at least the late 1990s. There are some minor internal differences, but they'll bolt on and work just fine. I've yet to see a later backing plate that didn't have the fifth mounting hole in it, even though it wasn't used. Make sure anything/everything you replace (hardware, springs, shoes) is from the same year/make/model, although you may want to play with wheel-cylinder bore sizing to better dial in your front/rear proportioning. Again, those are fairly universal from the '60s until the late '90s.