Test servos... ummmm can't really. They use a fairly complex signal... I've heard of computer programs that can do it, with a serial port interface... But mostly just find someone with a car that you can borrow to test with.
15 year old car eh? Gas or electric? If Electric, probably no problems. You might break irreplacable parts but I'll leave that decision to you.
Traxxas ERBE, 2Slash, XO-1, Associated SC10FT, Frog, 5th Scale Titan, and a small air force.