I don't know if the 74 axles are the same, but I used the longer axles (from a 71, I think). There was about 9/16" of a gap. The shoulder for the bearing was long enough on the axle, however. I found that a 74 drum closed the gap perfectly between the 69 backplate with the longer axles. This drum is for a 2-3/4" pad, but I have the 2" pads on the 69 backplate. There is a picture of it on my website....
http://www.classicplace.com/truck2.html
Greg