You don't see those very often. I cannot tell from the photo which warhead is on it. Does it have any markings stamped into it?
The rocket motor is the older 2.75" Folding Fin Aircraft Rocket (FFAR). I believe most were white in colour, although I think there were some grey ones as well. I will have to see if I can find my info on them.
The newer rocket motors have helical fins inside the venturi to impart spin on the rocket and three small folding fins.