Ditto. Hobby People should be able to provide the part.
I expect your ASP has a round cylinder head, but there is probably a "weedeater" style head version also. I'd ask for the XL .40/.46/.53 part for a round head ASP, but an XLS part would fit the "weedeater" type. Their techs seem to be real good guys, and should know or be willing to find out.
The Magnum/ASP's are all collet locked types, like ST's. If the front bearings are the same PN, then the prop driver will probably fit. Sadly, their online parts inventory software is a PITA. I've not found a way to electronically search for a specific part on Hobby People's site.
Steve