Well here's what I think I found out; The GT225, GT235, GT245, LX280, LX289 and GX255 all use the same frame. The GT225 GT235 and GT245 use the Tuff Torq K71B transaxle. The GX255 uses the K71C with differential lock. So you should be able to exchange the K71B and K71C. The K71C is also used in the GX335 GX345 GX355 and the GX255. The K71A is used on some of these too, but that does not have differential lock apparently. So, you should be able to swap out a K71C to get differential lock. I can't find where the GX345 or GX series used the K72. The GX series used the K71 series. The K71A without diff lock and the K71C with diff lock.

The new X300 and X500 series use the same frame AM137099. The X300 uses the K46 transaxle. This is also used in the L120, L130 155c LA130, LA135, LA140, LA150
LA155, LA165, LA175 X300, (X304 after 2007) LT160, LT180. The X534 and X540 use the new K72A transaxle with hydraulics and other X500 series use the K72C with all wheel steer. The earlier X304 used the K58; which is also used by the X320, X324, X340, x360. I can't find yet any connection to where a machine that fits the K71 series will also fit the K72 series.

Anyone know if the K72 series is a bolt on replacement for the K71 series?

BCF: I can't answer the question about the K72 Vs K71 interchange.

I can vouch for this though: My Simplicity Landlord DLX (2000 year model), and it came with a K71G. I found two K71E transmissions that had the differential lock. Both were NOS with Simplicity numbers on them.

I had absolutely zero problems with doing the change over to attain the differential lock. I did have to purchase the linkage for the differential lock, and cut a hold in my fender pan for the linkage to pass through.

It works like a charm.

A gentleman in my area was looking for a Tuff Torq transmission to go into his John Deere. I want to say it was a JD 235 or something like it. He bought my Tufftorq 71G and e-mailed me back later saying he was happy as a lark. I do not know if he had to change some linkage or not. I kind of doubt it.

That being said, please call Tuff Torq and speak to one of their tech support/engineers. They are great people to work with, and will give you the kind of answers you need.

Toll Free 866-572-3441

That's as good of advice as I can give you.

Cheers!

Hello there, did anyone ever actually do the swap from a k71 to a k72? I have a GT245 and am interested in doing the same. Thank you

Pat Wall, Call tuff torq at the above number and ask their parts people. I think a guy named Derek helped me at one time. They're good people to ask.