[orbot]

Why not put gears in it as the old axle??

Well then just see whats best

9"
Axle shafts will be around $180-250 a set pluss lug stud or new rear wheels depending.
adapt the braking system
convertion u joint
cut and weld the leaf spring perches
parts for a 9" are more expensive compared to the chevy axles

Old axle
new gears wich with luck you could get cheap and while you are at it service the whole thing with new bearings and seals.

Now let me ask you this how did you breake the u-joint??? cant you just get a good quality one.

Now if you are drag racing or going through new rear tires every so often the i would say put the 9"