Guys, after making countless calls on the part numbers given and others found in the archives, I came up empty handed. As my last resort, I went to my local CarQuest and found a green neoprean o-ring for A/C the exact size, and it only cost $1. So far, so good. I'll keep my fingers crossed and hope for the best at this point.
The John Deere shop was currently out of stock, and the Cat shop said they don't carry. In the near future, I'll pick up one from John Deere and have it onhand (or two knowing me and my fat finger).