I can get a free rear end out of a 80's V8 Llincon will it have a ford 9" in it?.....If soo how much do you think would fabrication cost for making it fit to a third gen.?...thanx

 

Providing it's roughly the same width as a third gen, that's the first step to making it work. You would have to cut off all the mounting hardware from the 9" housing and weld on all the mounting hardware from a donor third gen diff.

You still won't be able to easily attach the torque arm since only a third gen diff has a mounting pad for a torque arm. You could eliminate the torque arm by converting the third gen rear suspension to something like ladder bars but that's even more work.

By the time you're done modifying and converting, it can be cheaper to just buy an aftermarket bolt in 9" housing for a third gen.

 

basically if you have the skills to look at it and figure out how to swap it(welding, fabricating, etc..) and the width is close, go for it. If not, then yes, it's cheaper to buy a 3rd gen specific 9". - If the width is off you'll have to be shorten the axle tubes and get new axles.