Took me a couple years to find that thing...I love it! They pop up on Ebay from time to time. Have you been looking very long? There are a few out there, takes some effort to track them down. I came across a few in my search a couple years ago. Got mine for $400 and the dude delivered it for free Had another one lined up but the owner sold it out from under me.
Any one here still have a stock ring and pinion for sale. I pull my front axle apart next week and am almost positive I will need a new set. Mine have 240k on them and howl really really bad. Let me know.