I'm building a Dana 60 for a '71 cuda. The starting point is some van axle with way greater offset than in a passanger car. I need to know how much longer the axle is on the drivers side than on the passanger side? And what is the axle tube length difference, how much is the pinion offset from center to the passanger side?

Make the driver's side tube and axle 1 3/8" longer than the passenger's side. This will yield a stock Mopar passenger car (1 3/16") pinion offset.

My calculator below will figure housing/axle dimensions for most popular rearends in stock and custom configurations:

http://www.doctordiff.com/axle-calculator/

Are you wanting the stock E body widths and measurements? If so hopefully someone will post them for you If your wanting to use it with wider wheels and tires then it can be narrowed to what ever width you want or need

Dr. Diffs Calculator works AWESOME!

Thanks doctordiff!
The axle will be wider than stock, 63.8" from wheel flange to wheel flange, use new big ford ends and wilwood 11" (2.5") discs.