new to forum, have rear end question

thanks for the advice, i am glad i found this site. I have been on the slantsix site for a while, but this project (6 to 8) is unforgiveable over there! anyway, so you guys think the 7 1/4 will be ok? To me economical is when i can go to the junkyard and pick up a complete setup for $100 bucks or so. I did a lot of work with gm stuff in the past and the rear ends were very interchangeable and cheap/easy to find, etc. Even for posi. I have 2 dusters now, one 70 with a slant and now the 73. I have found the parts to be a quite a bit harder to find, more expensive, etc. It is worth it, though, because in the past 2 years i have really become a mopar fan, especially the abodies! Someone said that a jeep cherokees rear might fit, anyone have any more info on that? I have not been able to find any a body rear ends locally (massachusetts) at all.