I used to work on Diesel generators, and got fairly detailed files from the engine manufacturer.
The interior of the engine was greatly simplified; e.g. the camshaft and crankshaft were represented as straight cylinders, with correctly detailed flanges at the exposed ends.
The models were supplied in some 'neutral' format that I don't recall, that could be imported to SW, and were detailed (on the exterior) right down to the split lockwashers.
... which were a huge problem, because the angled split surfaces came into SW as some sort of Mobius Strip like entity that caused SW to choke, so you had to replace each and every one of the damn things with a better model before SW could use the assembly.
I suggest you do something similar, e.g. supply a 'dumb solid' model of all the exterior interfaces, omitting the interior intellectual property or greatly simplifying it. ... and supply a simplified model of any lockwashers as well.
Mike Halloran
Pembroke Pines, FL, USA