It is probably dependent on which engine and transmission is installed more than 1/2 ton vs 3/4 ton suspension. The long bed trucks normally have a 2 piece driveshaft while short beds have the 1 piece version. Some of the compound low 4 speed transmissions have a bolt on yoke against the transmission, while others have a conventional slip yoke. Powerglides, Turbo 350's and 3 speed manual (and early 4 speed passenger) transmissions normally share the same (smaller) yoke, while Turbo 400's and never 4 speeds like a Super T10 and late Muncies share a common (larger) yoke.
There's generally 2 trunnion sizes, large and small for both GM and Ford applications. If you end up with a mismatch, most parts houses carry a "combination" joint which has small caps on one cross, and large caps on the other, and they work fine:
http://www.dennysdriveshaft.com/p46...ination_u_joint...spicer_greaseable.html
