Cub Cadet has two (2) different PTO rebuild kits. There are Kits for the Narrow Frame (NF) & Wide Cubs (WF). The 129 is a WF.
Now during that product CC, changed the design of that PTO to comply with Gov't standards. So, they implemented a PTO with a brake provision.
So, you will need 759-3489
For more information, see..... PTO