I just rebuilt my RCK60B_22BX mmm. If you go to tractorsmart.com, you can down load the parts manual for your mower deck, tractor, ect. With the parts manual you can also order parts from there...
If the 24b is like the 22bx then there is an oil seal which seats in the gear box on the main shaft prior to the pulley. I would imagine that this is the case, but the parts manual will show you what is there for sure...
Good luck