12 Bolt axle swap?
 

I've got a friend who has a pair of axles from a 73+ 4x4, the rear axle is a 12-bolt, 3.73 ratio with 8 lugs. He says it came from a leaf spring 3/4 ton 4x4 truck, and wants $50 for it. I'm kinda interested in it - I'm curious if

#1) this 12 lug will bolt into a half ton 67-72 leaf sprung truck
#2) I can swap axle shafts from a 6-lug truck and keep 6 lugs all around instead of changing rims

There is no such thing as an 8 lug 12 bolt. They are all 6 lug or 5 lug. If the axle is from a '73 and up 3/4 ton, it is a 14 bolt, either the 9 1/2" semi-floater, or the 10 1/2" full floater. Any axle from a '73 and up 1/2 or 3/4 ton will have the wrong spring pad spacing and shock mounts for a '67 - '72 truck.

I was going on what he said, so I guess I'll assume its a 14 bolt - is it safe to assume there aren't 6-lug axles available for it?

If it is a semi-floating 14 bolt, there is a 6 lug version, but it was only used in '88 and up trucks. I am not sure if the axle shafts will interchange with the older axles.