45 shortbed question

[bugsnbikes]

How far back can the rear axle be moved via hanger relocation (for lengthening wheelbase) on a shortbed 45 before needing to cut/ lengthen the frame ?

 

[whitey45]

I did Chevy 63 rear springs, and got 8 inches of wheelbase. Shackles were at the very rear of the frame, killer flex!!