Are the splines that go into the clutch the same? I was wondering because I wanted to know if I could use a b-series twin disc clutch on my d-series? I think to do it on h and b you just have to switch flywheels.

 

No.

A little searching and you would have found this out.

 

LOL if that were the case, people would be doing swaps like crazy. lol Don't make the little guy hurt more than he already does.