Marty/Possum...
Grigg is still the man to try to contact about this. I started a project to to the Dana 80 swap on a '50 GMC 2-ton. The rear axle was only going to need the perches cut and rewelded. The front axle was going to need more work. We were thinking we would just swap the Dana spindles onto the existing axle (with machine work and bushings, etc to make the king pins work) because, if my memory serves, the Dana front was going to need to be cut.
I sold that project to Mongo so maybe he can fill you in a on what happened next.
The bottom line is that it is *not* a simple swap. There is a lot of measuring and machining to do to do it right. BUT ... given patience and dogged determination (and more than a few $$$...), it *is* doable and will yield a great set up. Again, though. with the power discs all around and the tall gearing of the Dana 80, this is only worth doing if you are also upgrading the rest of the driveline. On my project, it had a 4-53T Detroit coupled to a 9-speed Road Ranger trans. Your original 216 0r 235/SM420 set up will not have enough power or torque to make this axle swap viable.
Ed Pruss may know more than he lets on about this, too....
John
