Anode Rod

I recently winterized my TM 2619.  When I drained the Suburban brand water heater I found that the alumimum anode rod had deteriorated significantly.  It needs to be replaced before charging the heater next spring.  Does anyone know where I can obtain a replacement part?  My manual states that the rod should be replaced annually.  If you have replaced the rod in your TM and know of a general supplier, I would appreciate a response.  Thanks.