I think U2slow posted the widths on front Dana 60 at 67 1/2" and the rear SRW Dana 70 at 65".
I have been looking at other options for the rear, like wider and disc brakes. All the newer Dodge stuff is too wide. I have never seen a Cab and Chassis axle for sale. It might be the right width but no discs?
In my searching, it seems like a GM application AAM 1150 just might be right, maybe. Can't find out for sure just how wide it is. HOW HARD CAN IT BE? So what I found is that maybe it's 68", this would be good. I want to be at least the same width as the front. Wide is better with a cabover camper.
The problem is this will involve a gear change. Doesn't look like any modern axles use 3.54 gears! I wonder if 3.54 is available for the AAM1150?
Just doing some mental rambling on the downhill side of the Fauci Virus. I better never cross paths with that mendacious evil little gnome, oops rambling.

 

No 3.54 in the AAM1150 axles. 3.42 or 3.73 is the closest.

I do not feel the newer dodge diffs are too wide. (I run a 70" SRW D80.) Good choices with wheels and/or spacers will mitigate it. I've just let the rear tires hang out the last few years. The C&C should be a couple inches narrower (and disc for 01.5-02) but yeah, might not be an easy find. I always suggest www.car-part.com for searches. That diff however may fetch a premium as the customer base is commercial.

 

Man, that car-part.com is addictive! I can swap the front to 3.73 to match a rear axle. We'll see.