1970 duster-modified on a budget

Thanks! Still trying to decide what rear end i want to use. If i stick with the 8 3/4 i have to get a new third member and the whole shebang but im leaning towards either a 9inch ford or the 8.8 from a mustang because parts are really cheap and easy to find. Also the 8.8 had disk brakes on some of them and my local salvage yard is stupid low on prices lol like $100 for a complete disk brake rear end low