Don't if your asking me? You need the cup for both 10.5 or 11"not sure about the 172 tooth flywheel. There are 2 holes in shield to mount the cup hole nearest center 10.5 outer 11". The cup keeps starter nose in place and is mandatory IMO.OK, dumb question......do you are have a 10-1/2" clutch (130 tooth flywheel)? You only need the "cup" on the 11" clutch (143 tooth?) Sorry if it's a stupid question since you're looking for this part. Also, you might check your trans front bearing diameter. The original Lakewood scattershield "kit" came with some adapter rings for trans vs. large hole.
I am using my "offset" & cup (I'm running 10-1/2" clutch), but I do have some extra adapter rings & some hex-head bolts. If you need them send me a private message & I will send a picture to your phone or e-mail of what I have.