I'm located in northern California, I have a long nose R200 that is a 3.9 when I purchased my '77 280z parts car for the A/C system the kid through it in. So I don't know exactly what year it came off of.
All I can tell you about it is when you spin input shaft one direction its nice and smooth, when you spin in opposite direction not to smooth. I think they tried to mess with it and realized they didn't know what they were doing.
If you are interested let me know
Thanks Daniel