By feel, the XS mounts seem a little stiffer, but keep in mind it is just the uppers that are different, so it is not significant. It really needs solid mounts, still quite sloppy. I think only one other Allison ran the 150 four stroke, a ProSport, but I could be wrong.
I was wondering if the Racing V8 mounts would fit on the V6? That's interesting about the Sportmaster. I have a project in mind for that engine! Racing should have done a 225R V6!