Most guys that center the wheels in the fenders locate the axle about 1 1/2" back from stock location.
3100 wheelbase is 116" and 3600 is 125.25".
"If someone can tell me how much to cut out, I could go ahead and get that work done so I can cut down a driveshaft to fit my newly rebuilt 292/700R4."
I'll let you do the math...
You could always consider consider keeping the original wheelbase and not hackin' her up. Chicks dig the longbox you know.
Welcome, and good luck with your project.
