I haven't measured the mother leaf to get the exact measurement. I just measured the leaf springs eye to eye straight across.

Yes my rear springs are Chevy front springs which fit perfect in Nissan factory leaf spring brackets.

So new question about these chevy springs I got, I always hear about shackles being to long and damaging the spring. Is this true and what is it that damages the spring? Reason I ask is I have some shackels laying around that I was going to use but didne want to mess up the spring if the shackels are to long.

You might be able to overflex them with really long shackles. That's about the only risk. Good aftermarket springs should be less succeptible to this than the stockers tho.

So invest in some good bump stops eh?