The way that whole 5th gear / reverse shaft goes together there near the end is slightly different from model to model. My 87 was quite different from my 93. The 87 had no provision for a stopper, but the 93 required it, and oh yeah, it went on in a particular direction (found that out the hard way). Anyway, if worse comes to worse and you know you've got all the parts necessary to put the shaft back together correctly with the exception of the snap ring, you can size up replacement snap rings for automotive air conditioner compressor clutches as a direct replacement. Believe it or not, I found the correct size for my T-5 this way and it worked fine at least until I sold the car, 88K later. OBTW, you're paying a couple of bucks instead of Stealership prices. Not to mention, I'd be surprised to find that Ford would sell you the proper piece, anyway - the listing they show that was updated in their lates CD catalog is probably only available for purchase as part of a rather expensive kit that isn't even applicable to your model.