Sorry i forgot to answere your other question

the ESC is actually the speed controller or electronic speed controller (esc)...it basically controls the motor functions
on standard brushed motors there are two wire controllers and three wire controllers for brushless motors

you dont see an esc on your stryker because its built into the receiver that came with the stryker (you know that thing encased in the yellow plastic? thats your Rx or receiver)
the stryker b do not use standard equippment just stuff made specifically for parkzone.. which is cheaper...not of less quality mind you just cheaper in cost, but they are appropriate for what they do and as such they are proprietary meaning they cant be used with anything else but what parkzone makes (unless your really crafty about it)

the stryker b are usually grey camoflage and use brushed motors and nimh batteries while the stryker c are tiger camo with brushless motor and lipo battery check it out on parkzones website or horizonhobby.com
the stryker A isnt sold anymore you will only find stryker b or c

again dude good luck

xero.