Hi I have a 1967 Riviera GS and have just blown the diff. What kind of diff do I have 8.2" or 8.5" ? Where is the best place to get parts ? I don't know what is wrong with it but it is making a clunk clunk clunk sound as the drive shaft turns .It is at my mechanic at the moment. I'm in New Zealand so finding parts here is impossible . Thanks.