Sodom

Hello guys. I am in a confuse state right now and need help here. I just purchased a Fioroni centre torsen diff from ebay which says its for kyosho mp777 and 7.5 . Its second hand stuff. The problem now is that I cannot fit it in my MP777 sp2. The drive shaft from 1 end to the other is longer than the stock diff found in the buggy. And the centre bulkheads wont fit perfectly at one end .I have contacted the owner and he said it was used on his Mp 7.5 before. Is it possible that the MP777 sp2 and 7.5 diffs are of different lengths? Please help. I have also attached pics. Thanks