Opportunity for rear discs?

[Southpa]

OK, heres the scenario, I need some quick info in this matter. About 10 years ago I swapped the front end in my 70 GMC for a 71, so now I have front discs and 5 lug wheels...but still have drums and 6 lug rear. A guy at work is offering me free rims for 5 lug so I've been looking around for either axles or rear end for the truck. Currently its coil springs and 3.08 gears. I saw an ad ... THIS ONE : http://www.usedvictoria.com/classifi...embly_11928689

for this complete rear end package off a 79 Caddy seville. I read on this forum that some of you people out there have been installing rear discs of 78 / 79 Cadillac sevilles on their 67-72 trucks. CAN I USE THIS? Will the fact that the caddy rear end is leaf springs cause me problems either way? I thought I'd start this thread first and then begin my search of the board because I don't know how long this deal will be available. Any feedback regarding leafs/coils, bolt pattern, gears, width between rotors etc. muchly appreciated!