your friend most likely has a toro ccr2450. i took a toro ccr3000 engine ( 2 cycle ) and put it on a ccr2450 frame years ago. i already had all the parts so i didn't need to buy anything but nuts, bolts, and belts. the motor bolted on with no problems but but the fuel tank was too far out of alignment. i got a belt for a ccr 2450 and ccr 3000, i don't remember which one i used and i know i used a few longer bolts and washers to align the fuel tank. i got it to work even though i don't like it, won't loan it out, and won't sell it. all in all i don't think it was worth the time something i think your friend will find out if he can do the swap, find another ccr 2450 for your friend