Here's a summary of what Tom provided earlier:

[Update Notes from Tom Irwin: There are two TSBs addressing this issue, 221943 in March, 1997 and 221945 in June 1997. The one from March 97 was superceded by an internal document dated November 1998, that was a Service Bulletin, titled as a "troubleshooting procedure". Here is the BAD NEWS

guys...it covers 960 from 1992 through 1994... they went cheap even at that stage and authorized only a block swap with some incidental parts...the original engine gut pack had to be swapped. They called it a

"defect" and allowed 20.4 hours for the swap.

That is for the 92-94 cars and I don't have block number references. This latter internal document references block numbers 25000-52873 which would seem to take the problem into the 1996 model year.

Any 960 owners of 1996-1997 cars: what is your engine block number and date of manufacture? Let's try to pin this down.