How do you know if you have a limited slip 901? Can you check like an old gm posi, where you jack up the car and turn one tire?

Was it an option from the factory?

yepp

M220 - 80% limited slip differential

Gustl

You would get the information off the window sticker or COA (notoriously inaccurate). First thing I would do is go to Vegas and bet millions against it. Pretty rare.

Can you confirm that it was a line item option on any 914????

That would be a major coup...

-Josh2

A real clutch type limited slip (factory option) would roll both wheels in the same direction if there is no load, and even then..that is not consistent.
If the clutch pack is worn out, or set up for less limited slip, it may not turn at all...

The Quaife type limited slip, non factory, will behave the same as an open diff when you turn the wheels..so that should drive you nuts.

Best way, pull the gear stack and take a look.

Rich