M and F body 2 dr. are 108" wheelbase. Same length leaf spring? I have Caltrac on my '80 Aspen. The '81 Diplomat is going to be a race car. Same spring and rear suspension set up?
Yes, same springs, same hangers, same shackles, same iso-mounts, etc.
Actually, 2-door, 4-door and wagon are all the same,,,,,,,,,other than maybe if it's 4 leaf or 5 leaf.