How can I know if I have factory LSD
 

Title says it all. I have a 78 SC. A mobil mech once told me I had factory LSD. The car was jacked up with both rear wheels off the ground. He said that when you move one wheel and the other one moves as well, reverse direction I think, that means you have LSD. Coulda been total BS and I wouldn't know.

This mech turned out, some years later, to be a total criminal/thief/liar and is now headed for the gray bar hotel...none too soon either, but I digress ;)

If the opposite wheel spins reverse of the direction of rotation it's an open diff or a worn out lsd. If there's a functioning lsd in there both wheels will move the same directions when spun.

Yes, and right after he found out it had an LSD in it he said "oh leave it here for a while" then he took it out and put in an open diff.

OK...answers my question. It spun the opposite direction. Thanks

Factory limited slip would also have "12" in the middle of the serial and type numbers stamped on the bottom of the case.

http://forums.pelicanparts.com/porsche-911-technical-forum/348159-915-trans-limited-slip.html

I have 12 in the middle is this factory LSD 915 santa is kind to me or i am just dreaming of that LSD

http://img1.classistatic.com/cps/kj/...3024ll_20.jpeg

Please let me know. Thanks again

having an LSD can be determined by wheel rotation as mentioned above but the question was a 'factory LSD' which Wil correctly identifies as having the /12 stamped on the case. Mind you, if it was a factory lsd in 1978 I can't imagine that it is holding much more than a few ft lbs of torque before slipping unless it has been freshened at some point.

up the rear wheels (in neutral) and a Giran if you set nal LSD original ..

Without rotating anything the serial no for my gearbox says i have a factory lsd right?

Thats all i am asking without my functing fuel distributor i am stranded for now.

Stranded or not with regard to a running engine..... factory fitment would be indicated by the "12"...and "functioning" LSD would be as stated....wheels in the air and hand-spin. If opposite wheel spins in same direction, then there is functioning LSD, if opposite wheel spins in opposite direction, then no LSD "function"... acts like an open diff. You don't need a running motor.