BROKENHIP,
Here is another site to check. Check both the 1996 and 1997 46" lawn tractors. In case I was not clear enough before, if you come across several model numbers that look similar like these...
42917x6A - Lawn Tractor (1996)
42917x6B - Lawn Tractor (1996)
42917x6C - Lawn Tractor (1996)
42917x8A - Lawn Tractor (1996)
42917x8B - Lawn Tractor (1996)
....You just need to click on one of them. If the number in red is the same, the tractors are identical. The x?? number is just retailer info. Hopefully I'm not over explaining.....
Just for the heck of it, in the mid 90's, Wal Mart was the major retailer of Murray equipment. I'm not sure if this was a chain wide policy, but I have seen several tractors from Wally World that had the Murray model number and the Wal Mart store number engraved into the metal under the seat. This was a security measure and was done at the store level, not at the Murray plant, so it's literally just scrawled into the metal by whoever was told to do it that day. It's a long shot but worth a look.
http://www.partstree.com/parts/?lc=murray&mh=8