Thanks all for the responses!
I had checked ebay, and a host of other sites. Called 4 Subaru dealers for parts diagrams, but none have any that go back to the 80s. It is item 10 in from Silverhelme's post. That diagram is from the Haynes manual.
I ended up going with making a new one. Last night, I went to Home Depot, bought some clean Sheet metal stock, 22 or 24 gage thickness and traced over the with part #9 above to get the outline of the washer. I drilled out the center and filed out the Inner Diameter and was able to get the nib or tang in place with a small file and metal blade. I cut out the general circular shape and used that to get the job done. A little crude, but it worked! Using some pliers and other tools I scored the edge that fits against the D side of the thrust washer and was able to get a good bend to align with that flat side of washer. I scored two edges and got a bend going so once I put the nut on, I could finish tapping down the two edges against the hex side of the nut. Job done!
The thickness of the metal I bought was about the thickness of a license plate and it was the same as the original washer. It was bendable enough to cover the nut.
Again, thanks for the suggestions. If anyone finds them selves on this thread looking for a solution, I would recommend making your own. If the part number for this washer could be located, its possible it could be found somewhere, but without the number, its not locatable. Dorman's online catalog of 1000;s of parts has the nut, thrust washer and other part, but not this lock washer.
Regards,
Mal