I just looked at the two brushless on the Cen site and all of the big monster trucks will handle 4S, so 3S should be fine. Pick you're truck, then on the right, click the esc manual. Look down to the batteries and look for the cells under lipos. Everything I saw on both brushless versions will handle 4S at least. The EZ Run 150 amp will handle 6S. The EZ Run 80 amp will handle 4S max. So you should be golden.

http://www.cenracing.com/cars/8th-MT.html

Eta make sure you don't throw 6S (2X3S = 6S) at a 4S Max (80 Amp) esc. That won't end well lol.