re bevel box gears - an observation.
I am no expert in bevel boxes or gear types , but I had the opportunity to examine a brand new one not attached to a vehicle recently and was quite surprised how stiff it was to turn over by hand ( i.e. nearly impossible ).
Turning the prop shaft input was impossible , and I could only just turn the output shaft.
This surprised me - I didnt expect to turn like a bicycle hub , but also didnt expect flat resistance to the input !
No wonder the horses disappear in the drive train !

Does this fit with anyone else's experience ?