popsracer - no worries! im glad to help, returning the favour after telling me to use those black kyosho springs in my reflex a while back.... i find my mugen centax is heaps reliable, never had a problem and i have never had the engagement point change or any of those problems.
im not sure about the part numbers, thats what it says on the packet my centax came in but it wasnt the mtx 3 specific centax it just said MRX/MTX racing clutch set.... the difference is the flywheel i believe, otherwise its all the same!