First off I must say that dont let anything I say discourage you from looking into purchasing a copy of this fantastic car. I recently purchased a '92 lsl with 99k on the clock. Prior to purchase I was in contact with the previous owner and she was still in contact with the original owner. Both were older professionals that had taken emmaculate care of the vehicle. When I purchased the car it apppeared to be in good condition and drove nicely. Approx..2 months after I bought it the tranny went.
I recommend if possible you have the tranny looked at before purchase. My mechanic charges me about $300 for them to drop the tranny and take a look inside. You might be able to get away with just checking the fluid but either way it will be money well spent if they find something wrong before you buy it. Otherwise you could be loking at about $2500 to $3000 to replace the tranny soon after purchase.
Like I said dont get discouraged by what happened to me. There is no reason not to expect that tranny to last for a while after you by it. And if so you get yourself a one of kind automobile. Personally I dont regret buying mine at all even with the repairs I've done. It is an awesome car to have.