The rears are 18 x 10 with 4" backspace.
I've settled on 49 5/8" planned for the disc to disc diff width. This provides 1 1/4" space between the frame rails and tires and about an inch where the upper well curves in toward the tire (with the mocked axle on frame bumpstops).
This is the exact measurement that my drawings that were made using a plumb bob and just fiddling with tires in the wheelwells had suggested. I wanted to be sure before sending out axles to be cut.
The 8.8 I'll be using has a 2" pinion offset to the passenger side. Since these cars come with a similar offset (something like 1 3/4") I'll likely take the same off each side. The 8.8 is 59.5" disc to disc, so that will mean 4 15/16" off each side. The minimum cutoff according to Dutchman Axles is 3.5" so I should be fine.
