I am building a narrowed Dana 60 for a dart and it needs to be 46 1/8 axle flange to flange. When I ordered axles they made one shorter than the other, I told them that it would be the same pinion offset as mopar used on the muscle cars. I think it is 1 3/16. I didn't realize the dana had different length axles.
The dana I got came out of a truck and since I was going to narrow it anyway I didn't figure it mattered, I would just put on the mopar ends. When I tore it apart I noticed the axles were the same length and the axle tubes looked like they were the same length, the axles were 30 spline but I am changing to 35 spline. When I measured pinion offset it was only 1".
So I am not sure how to cut the axle tubes to get the right width and offset. One axle is 21 3/8 and he other is 22 3/4

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"

Thanks dr diff. I realized later that it was 1/2" offset, I will just blame it on monday. I get used to the 8 3/4 and the dana just threw me off. Your measurements worked out right. Thanks

We always made tubes the same lenght just more room for brackets