I recently bought a street rod with a 9 Inch for rear... its all painted up and pretty, but unfortunately its an open differential without posi (or whatever non-Chevy guys call it) Can a posi carrier be bolted into this rear without a major hassle? Do all the axles, etc. still work? Can I use the same 3.00 gearset? And lastly, where's a good source for rebuilt posi units? I'm not too experienced with Ford rears, but am hoping its an easy change to make... pegleg burnouts aint cool.