Rear Spring rattle

[ODZKing]

I spoke to Tom over on the third gen forum about this but wanted to see if anyone had run into this issue here.
I swapped the differential on my 73 with a 71 rear. Thinking it was the same and everything was fine but I have been fighting a rattle. The jackass who installed it for me never told me the shock/sway bar plate didn't sit flush and is rattling all over the place. He kept saying the exhaust was the problem. 
As mentioned, Tom said the plate and/or the mounting hole the spring bolt sits into is different. Has anyone performed this and what was the eventual solution?
There are some things I just can't do without a lift and when don't do things yourself and you depend on other people, many times they disappoint.
NOW, this will cost me twice as much to get remedied.