You're going to have an interesting time finding a new replacement (based on the updated model number). I went through this very exercise with my '02 Adventurer that also has the Basement AC Unit. Scoured the internet for weeks, and each outfit I found that had the new unit for sale actually had the listing for no inventory, but for you to just get on back order and hope you get one within 3+ months. Not ideal.
The part number 46515-811 is exactly the same one I had been searching for (with the left side discharge) - but no luck finding something immediately. Biggest thing you need to check for (like John said) is verifying if its a top or side discharge.
If it's an immediate need, you're going to have better luck checking a salvage yard for a unit that was tested out of a parted out coach. I will strongly caution you to get everything in writing, and have them send you physical readings of all test results should you find one. I had purchased a salvage unit that was supposedly tested from a Salvage Yard in Arizona, and upon receipt and testing before install, we discovered compressor 1 to be grounded out and shot. Contacted them for a replacement, or for a credit. Got a one line email saying 'send it back' and no further follow up on a return PRO number, pick up, scheduling or anything after a few phone calls.
Opening a dispute for partial payment, since I am just having a local HVAC guy replace the bad compressor - and I'm going to have the second one replaced as well so I at least have a 'new' unit.
I still have the original unit that was taken OUT of the coach that I bought, which was having the voltage problem to the board as well as what appears to be a bad compressor on circuit 1 as well.
Once supply gets better and my HVAC guy slows down in the late winter, I'm going to have him fix that one up for me as well. Wouldn't mind selling that piece to recoup some of what I had to eat to get the other unit right. Based on the supply right now, I'm sure there are people out there looking for it.
Sorry for the long rant/post on this. I've spent enough time pulling that thing apart and finding parts for it.