19hp 42 inch cut Ariens with plastic transmission

[Tpieman22]

What would be a good transmission that will fit this mower without a lot of modification. This mower has the foot shift

 

[StarTech]

Another RS800P would be easiest without mods.

 

[Tpieman22]

This one is slipping bad in reverse thats why i want to change it out. have some john deere transmissions tuff torque