I'm pretty sure that would be an easy swap. The 3k's are different than the 2k's so you will need to reuse the muffler, manifold's, pto system and a few other things I'm forgetting. You will need to see where they pickup the vacuum for the 3k pto. It probably has a fitting on the intake manifold for the 3k machine but I'm not sure the 2k will have it.
Here are some free manuals if you don't already have them.
https://www.ccpartsnmore.com/cub-cadet-product-manuals
Good luck and if you have any questions we are here to help.