I finally got to the yard and pulled a used trac loc differential. It cam out of a 1979 F150 4x4 with a 9" Ford rear axle, with a tag that read 3L50. I took the center or 3rd member out, was told it was in good working order when the engine failed in the truck. I would like to know what these numbers are on the center differential. It looks like a tag is on the part, but it is really molded into the metal to look like a tag with two scews, it reads 9A10.
Then stamped below into the metal it reads W- 4205. Any help with these numbers, thanks.