Call Yokomo USA. There is probably a good chance that they still have them in stock. I know that they have alot of parts for the old MX4 in stock. I have ordered some in the past. Good luck on the phone call though. Everytime I have called there it is like pulling teeth getting them to answer. I think the part # is ZM117G2, there are two different part#'s I think that ZM117G is just the two piece version that the car initially comes with except it's graphite, the G2 version is the one piece I believe. You could also try ordering from Yokomo USAs site.
I just noticed your in Singapore. You could still go this route, I don't see why they wouldn't ship international or have your local hobby shop order one in for you.