Just for the hell of it I went on to carparts.com to see if any 87-89 300zx lsd diffs were in the area. To my suprise there were two places local that had 300zx turbo rears. The one junk yard I knew well and knew I would be close by today while at work.
I decide to stop by on my way back to the office to take a look at the diff and see what they would sell it to me for. I got there and asked to see the diff for some verification. The case itself was in great shape. It is only the diff, though, no shafts or other parts.
The first thing I noticed was that it had the finned rear cover. Yes, that is a good sign, although I thought I read that doesn't mean it will LSD on here. I then started looking for any distiguishable marks. Do they have any? there were a couple of numbers on the diff, but they meant nothing to me. I flipped it, inspected it for any marks or info on the diff but there were none. The only thing I know is that it came from a 5 speed '87 turbo ZX.
I then proceeded to ask the one gentleman how was I going to verify that this was truly a LSD. He pulled the one mechanic (I'm not sure if was really a mechanic, but the other guy thought he would know more) over to help out. The one test I know is to rotate one side and if the other side goes in the same direction then you have a LSD. No shafts, so that won't work . The mechanic pulled the cap off the right side of the diff and stuffed his fingers in there, he then turned the front flange where the drive shaft attaches. He did this a couple of times and then said that was a LSD because he was unable to stop the gear from turning when turning the flange. Does that really work? I know the other side was turning, too. I'm just not sure of that method, and if it would work.
Anyway I decided to buy it, and take the cover off for verification when I bring it home. I couldn't take it today since I was working not looking at parts for my Z . I'm hoping it is an LSD because I got it for $250, which I though was a good price. Oh well, just though I would share.