No, the kit only comes with Coldstream Guards decals. The rocket parts consist of two identical "G" sprues with 16 parts on each. Two of the parts are for the rear radio radio bin that you add to the rear of the turret so you end up with an extra British style radio bin.
Parts G8, G9, G10, G11, G12, G13 are side specific (you use 8-10 on one side and 11-13 on the other) so you end up with an extra part G8-G13. Parts G1-G7 and G14 (all times 2) make up the meat of the conversion which are the launch rails and the rocket.
Is the kit worth $25? Probably. You could also look to see if someone had the kit but built it as a standard gun tank and has the rocket pieces leftover. I do not know of an AM conversion, but then again, I do not know much about non-US tank Shermans.