diff width/diameters

[USA69Z]

Im going thru my truck at the moment and am about to start on rewelding saddles on the diff. The previous owner butchered the heck out of the rear and couldnt weld at all. The diff thats fitted in my 70 stepside coil rear end has been replaced with something?? its a 10 bolt with around 59inch flange to flange width and 2.60 diameter. he has left the old saddles on which are out wider than the 'half' saddles he has tacked on. Any ideas what this could be? does a camaro diff fit up? im in australia so to find an original is gunna be tough but possibly a camaro or ? could be located? oh yeah the rear now has the 4.75 5 on 5stud pattern.
thanx !