Kevin,

www.2weddle.com

Get the South African .457 ring and pinion 5 speed.  Costs a little more than
the .483 but gives you an overdrive gear, first gear is useable (with the
.483 I had to shift out of first as soon as I got moving, really low gear),
the oil fill hole has been relocated and is at the correct height (no more
guessing if you have enough oil), each gear range are better suited to the
engines power band and the transmission is built heavy duty (it has to hold
up to the SA 2.6L I5 engines).
For me, going five speed is worth it.

Robert