blau928

Hi All,

I recently purchased a used 80K mileage Auto trans and was told it was a verified LSD unit from an 87S4.

However, upon receipt of the transmission this week, and physical inspection, I am thinking it is actually not an LSD equipped transmission, so I wanted some help confirming this..

The numbers on the case are as follows:

Side near fill bottle: 722 270 21 01 722 326 02 923527

Rear Diff cover near drain plug: AT 79 200 455

Rear diff cover near speedo sensor: 928 301 306

K within a big G 27/11

The transmission is on a pallet, and I am not installing it unless I am 100% certain that it is an LSD unit.

I tried the shift selector in neutral and rotate the drive hub, and the other hub rotated in the opposite direction, so I am taking it that it is not an LSD diff with 2.2 rear end as I was told it was.

I am wondering if this diff was a retrofit, as I have another transmission that is open diff, and the rear case is as follows:

Rear Diff cover near drain plug: A28 12 16H 00 878

Rear diff cover near speedo sensor: 928 301 306

K within a big G 27/11


If unsatisfied, I have the option in writing and a paypal guarantee that I will be refunded the purchase 100%. I also know where there is another used LSD unit, and will buy that one, but wanted to be sure I have to go through the hassle of return shipping it to the seller and being credited for my $$$ before purchasing the other transmission and waiting on it being shipped etc.etc.etc....

Thanks for all tips, info, number deciphering etc...

Vilhuer

If it had LSD this number would be A28 12 12 16H 00 878. Since there is no additional 12 its non LSD version.

Thats how diff left from factory. If it has one now can be easily checked. Put gear into N and see what happens when output flanges are rotated.

blau928

Hi Erkka,

The one I have as a spare that is A28 12 without the second 12, i know is an open differential unit..

I was wondering about the unit labeled: AT 79 200 455, as i do not understand this numbering sequence..

I also tried the neutral and spinning the axles, and they counter rotate, implying that the diff is an open diff..

Anyway, thanks, the seller has already agreed to take the unit back and refund me 100%...

Regards,

Tails

The auto transmission is manufactured by Mercedes Benz for Porsche.

The number on the side is the MB manufacturing number and the last 14 digits (722 326 02 923527)
identifies the box type.

722 designates that it is Automatic Transmission
3 is the Model of transmission and it means it is a 4 speed/6 bolt/Large case (large oil pan)
the next two digits 26 indicates the type of Automobile or Version Number
02 is not described in the MB guide,
and the last 6 digits is the MB serial number of the auto box.

The A28 12 16H 00 878 is the Porsche number assigned to the box.

Unfortunately I don't have any information on AT 79 200 455.

Tails 1990 928S4 Auto