OK, with this information, I feel I can now contribute to the thread.Additional details...its more of a binding sound that can be heard with the engine off, transmission in N, while drifting down a slope, with the wheels turned hard left.
The early RTV's had a design flaw where you could turn the steering further than what it was really able to handle. I had the same issue you described in what I quoted above.
They created a kit to limit the steering a bit which stopped the problem. It's a simple kit with just a couple steel plates that mount to your lower A-arms. I did a quick internet search but can't find the part #.
Tommy (forum handle is Peanut), created his own limiters which is what I'm using on my RTV and they work very well.
Here's a thread on the subject. Maybe he still has the template or a set already made sitting on a shelf. I'd PM Peanut and see if he can help.
www.nettractortalk.com/forums/showthread.php?t=12317
Edit to add: I found some old notes on the Kubota kit. It says they're used/needed for RTV serial #'s from 10001 through 66026. They "think" they had the fix in on all higher serial #'s. The serial # is the last 5 digits of your VIN on the plate above your battery.
I "think" I saw a set of limiters on my shop shelf awhile back. Didn't have the mounting bolts but those can be gotten at any hardware store. If Peanut doesn't have what you need (I'd definitely go with his as opposed to the Kubota kit), I'll see if I can find them and get them to you.