Sierra drive shaft lengths?

Does anyone know the difference in lengths between o/s and n/s Sierra drive-shafts, I know there are at least three different types; plug-in, 100mm and 108mm but surely the difference (if not the lengths) should be the same.

My plan is to possibly use a sierra diff as the basis for the chain drive on a BEC-Midi. One problem often associated with BEC’s is that when fitting a chain-drive, custom drive shafts are often required to give the right chain run to keep the engine central. This almost always results in one drive shaft needing to be shorter than the other. My hope was that with Sierra shafts already being different lengths this might offer a solution that doesn’t require the expense/hassle of fabricating/buying custom shafts.

Being as mine is a scratch build I have the luxury of matching my rear track to the Sierra for convenience.

I have a pair in the garage I can measure in the morning but from memory there is about 50mm difference between o/s and n/s

Cheers
David

I have a pair of late push in type. N/S (left) 800mm and O/S 840mm.