my buddy is parting out his 69 caprice and we was wonderin if i could use his disc brakes on the front and use it on my 70 chevelle. are they the same size? what are the difference in that and the a-bodys? any help guys?

Won't work... you're better off selling them to someone with a 65-70 Impala

The spindle, rotors, and brackets are all completely different.