The correct way to do a swap is to swap the diff and axles together if they have a different sized c-clip than what you already have. you can just get away with swapping axles alone IF they had the same c-lips as what you currently have. Yes, in '85 they did change the c-clip size and yes, they are a bit different.

I asked Dr Diff about this sometime back and this is what he told me---and then I ordered a set of each c-clip from the dealer to have a look at them as I did not have extras around to compare. The difference is quite obvious.

Bottom line, the correct c-clips need to be in the correct matching differential and also have the matching axles.