i got what you need huckleberry.
well, i have a 10 bolt, just pulled it off of my truck. 1988 1/2ton silverado 280k but rebuilt 60k ago. measures 74 1/2"s from spring center to spring center. oh and did i mention it's 3.73 and has an auburn limited slip. i think $50 is fair. let me know if you're intrested. and it even comes w/ a gay chrome cover that leaks. oh and yes it does need a new axle seal on one side. see pics attached of axle. it's always had redline gear oil since i bought the truck 4 years ago.
Dillon Carson