9 inch rear with stock disc brakes...???

[troy54gmc]

Allright ive been racking my brain the last couple of days. Im putting a f--d 9 inch rearend in my 54 gmc but it didnt come with brakes when i bought it. its out of a 80s truck and is 65"s wide. I want to put discs brake on it but all the after market kits are really expensive. So i did some research and found out the 77-80 lincoln versaliess came with a 9 inch rearend with disc brakes stock from the factory, as did the granada and monarch. so i went to the junk yard yesterday and found 2 stock 9 inch axles with factory disc brakes 62" wide mounting plate to mounting plate on the 79 lincoln versaliess. they want $250 buck for one of these. I have read these axles came with really poor gears for hp more for car cruising. Has anyone done this swap and if so what problems did you have??? Or should i just save and buy a kit for the one i got? any feedback would be greatly appreciated...