The driver's side tube and axle must be 1 3/8" longer than the passenger's side to yield a stock Mopar passenger car (1 3/16") pinion offset.

In other words, your housing should be 40.825" wide with the driver's side tube 1 3/8" longer than the passenger's side (measured from outside edge of center casting).

BTW, stock Danas 60 truck housings have 0.5" pinion offset (1" pinion to housing end length difference/2).

The resulting Mopar passenger car pinion offset is 1 3/16". (1 + 1.375)/2 = 1.1875"