Having Dana 60 cut for my 72 Duster

Are you changing from SBP to BBP or is the 8.75 rear already big bolt?

If it's already BBP, Yes, 52 5/8 is the correct length. Make the drivers side tube 1 3/8" longer than the pass side to get correct pinion offset.

If it's not a BBP rear, then you need to shorten up the dana about 1/2" total for the different brake standoffs.