These [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJB22&P=Z]muffler screws [/link] should fit no problem...because the new Tower Hobbies .46 ABC engine is the OS .46 FP....when OS discontinued the OS FP, they gave the copyright/patent to Tower Hobbies who got someone to make the Tower Hobbies ABC engine...its identical to the OS 46.FP (also the .40 FP)....that is what my instructor said when I asked him about Tower Hobbies engines...I think I forgot something in the story part but the screws should fit....