***DISCLAIMER***
This is what I did and what worked for me. What you do is your own responsibility! This is simply a guide for me for the next time I perform this service. I am in no way a professional or somebody that repairs garden tractors as a profession. I am simply someone who has some mechanical aptitude and I know my way around a wrench. Again, what you do to your own equipment is your responsibility!
I performed a transmission fluid change on my lawn mower. I completely forgot to record unbolting the transmission from the frame! I was too focused on getting it out to remember to record. As well, sorry I didn't include the reassembly process. I really wanted to get it back together quickly. It's obviously the reversal of the removal process. Just make sure you get the drive belt around the transmission pulley before bolting back the transmission onto the chassis.
Overall, it's way easier than it looks. I gave an overview at the beginning of how the K57 is bolted and linked onto the chassis and levers. It's literally 5x 1/2" nuts and bolts that secure the transmission onto the frame and 3 clips/pins for the switches and levers. That's it! Basically 2x nuts/bolts on the left axel to frame, 2x nuts/bolts on the right axle to frame, and 1x nut/bolt on the front side of the transmission to a bracket bolted to the frame. It's almost scary how small the frame bolts that secure the transmission are. In my opinion, they should be a lot beefier (one of the frame bolts was slightly bent. Too skinny!).
Start with unhooking the linkages first then unbolt the K57 from the chassis. Make sure you support the frame before unbolting the K57. I made a make-shift gantry style crane using 2 saw horses, 2x4, and a ratchet strap to pickup the frame. I honestly think that was dumb and unnecessary. I could've just jacked up the rear and supported the frame with jackstands from the underbelly once I unhooked the levers. I ended up doing that anyways as seen in the video.
Also make sure the K57 is in neutral (gear disengaged) so you can roll it freely.
Once the K57 is freed from the chassis, you can easily take the drive belt off from the pulley. Just tilt it forward. Now you can roll the unit out.
I purchased this machine used. I'm pretty certain the K57 fluid was never changed. It was black with tons of metal glitter!
The mower started getting noticeably slower as I mowed. It's about a 2 hour mow and by the time I'm done, it's near half speed.
Don't trust when they say the transmission requires "no service" and that it's a "sealed unit". Total BS. I wish I performed this fluid change sooner. I'm hoping this will help in prolonging it's life. I got the mower at around 1200 hours of use. It now has over 1400 hours.
The shop manual says to refill with 2L of 10w30 premium motor oil. But since it's getting old and sluggish, I opted with 50% 10w30, 25% 10w40, and 25% 75W90. Why the multiple grades of oil? It was what I had on hand. These were Amsoil and Motul synthetics I used.
Guess we'll see how it holds up.