I want to buy OEM LSD for my S2. My S2 has Swiss gearbox with external oilcooler but no LSD. Does OEM LSD have 2 versions one with oil pump drive other without it?

 

There's a gear that attaches to the differential to drive the oil pump.
From PET, the two gears are different, LSD versus non-LSD, but I don't know the differences or whether the non-LSD version of the gear can be adapted to a LSD differential.

 

Yes, two versions, but they cannot be interchanged. You'll have to get the LSD version of the drive gear to work with your transmission oil pump.

 

Will the LSD from 944 Turbo with transmission oil cooler will be plug and play or there is specific S2 version of LSD?

 

Any LSD (or open differential for that matter) will fit in any 944-series or 924S, they are all dimensionally equal. When doing the swap, be aware that you have to re-establish differential carrier bearing preload and ring-to-pinion free play (also called backlash). These are both adjusted via shims under the two differential carrier bearings' outer races, and the procedure is described well enough in the factory workshop manual. I recommend doing it with new bearings: they are inexpensive and it's much easier to set up new bearings than old ones.

Historical note: there were three versions of the LSD used over the lifetime of the 944 series.

• Generation 1 – the ring gear mounting flange was welded to the differential “can.” This turned out to be a bad idea, as the welds would sometimes develop stress fractures.
• Generation 2 – the mounting flange is cast as part of the differential can. ZF also upgraded to a better quality “GGG” steel in the casting.
• Generation 3 – used in the ’88 944 Turbo S and forward, with transmission code AOR. It had 2.50 mm clutch discs versus the earlier 2.00 mm discs, which were better able to tolerate heat energy generated in the differential. The LSD’s pinion shafts were also moly coated where the spider gears ran on them, eliminating a wear problem.

I would avoid using a gen-1 LSD in an S2 or Turbo, if at all possible.

Also be aware that just about any factory LSD you find has 35 to 40 years on it and is in need of a rebuild.