Electronics help needed!!!
 

OK, I know this will be a noob question, and I did do some searching, but this isn't going into a crawler, so I wanted some opinions... I picked up a new project RC truck and I'm going to make it into a basher more than anything else. It has a single motor (not sure of the size but it looks HUGE) and 1 steering servo. It is currently setup to run 7.2V, but I now have a few questions. The steering servo is weak, and I thought about replacing it. Then I got to thinking, hey! this doesn't have any speed control, it's either go or no go! Basically what I need is all the electronics except the motor. I want something that'll be reliable, but in-expensive. What do I need? just an ESC and servo? do I need to replace my controller? I'm just lost at this point and looking for some help!

Here's a pic of the motor

This is probably radioshack truck ?
So the motor is 550 silver can ( 27turn ) but to replace steering servo you need to replace whole electronics with proper esc and rx.