How far apart are the perches on a 10 bolt?

[K5thatShmobs]

Ive done some of my own measurements, but I was wondering if anyone knew how far apart the spring perches were on a rear 10-bolt on an '89 K5. (Also, note whether measurement is inside to inside, center to center, or outside to outside) I want some figures to compare my #s to.

 

[codeman]

Outside to outside, about 44 3/4".

 

[R72K5]

should be 42.5" center to center it if its 73-up, same if is 72 older and 2wd and not a longhorn or 1 ton or 4x4