yeah, what'sa matter with original??
there is no "best", just what's
your preference, or maybe "easiest"
in a 57, which had the 265/283 optionally, any small block is an easy swap, and the original 3 speed bolts right up, or newer 3 speeds, like 68+ which have a syncro 1st - also the original or later OD 3 spd is a straight bolt in, and eliminates the "need" for "freeway gearing" in the rear - nothing wrong with the straight axle in front, and if you think you need better brakes there's easy ways to add front discs
anything is possible, but study the situation and see if you really need to make a bunch of spendy changes to something that works fine as designed
yes the CDN 1300 is the same as the US 3100, all the model designations were different, but the trucks were pretty much the same
Bill
