leaf springs and spindles question

[Nukes16]

Hey guys I was just wondering if the rear leaf springs for a long box are the same length as those from a short box. Someone told me that the long box leafs are actually shorter than those on a short box. That doesn't make sense?
Also, my 81 3/4 ton has 8 lug 16.5" wheels. Can I replace the spindles on the front with spindles from my half ton ( with the 5 bolt pattern) and throw a 5 lug rear axle on of course.
What are you guys doing instead of running the 16.5" rims?

thanks again