The propane gauge broke off my 2013 Greyhawk 29KS which might be the same as you have.
I bought two of the replacements from eBay, see the pic for model numbers.
Installation is a 1 minute job as it snaps over the Tank Plug as shown in the other photo. The dealer says the plug has a magnetic piece that turns the magnetic dial in the gauge So there is no need to open the tank to replace this part.
Note: I had a leak at the plug as it was not sealed correctly at the factory. The dealer removed the tank, pressurized it and found the leak. They suspected the plug as the “odorizer” in propane left residue at the plug.
Good luck