6 lug rear to 5lug rear swap help?

[65Guy]

When i bought my 65 it had been converted to 5 lug disc in front and 5 lug rear. When i pulled off the rear drums i noticed that a little more than hlf the shoe was contacting to drum. In reading i guess that they are newer axles and it is unsafe. my question is on the 70ish factory 5lug trailing arm rearends are the axle tubes longer or are to backing plates longer or what is the differance. I need to fixit as cheap as possible. I dont want to buy new axles at $250. Thanks guys.