I bought a tiller from the same guy in NJ that had both.
You can pull parts manuals for both the 540 & 2000 rpm PTO's from Sonny's website. Yes, there is a chain in the 2000 rpm. I think the 540 uses gears.
I don't think Bolens made many standard 2000 rpm CAT 0 implements. I know Wheel horse had both a Tiller and a rear finishing mower set-up that way. JD may have had some too. Simplicity / AC Power Max tractors were heading that way too. So, any of those implements should work on your Bolens using the 2000 rpm PTO. IF you can use it with the 3 pt hitch. Has anyone seen them both on the same tractor?
2000 rpm & Cat 0 was supposed to end-up being more popular. But when the compacts came out, most folks wanting those kind of implements upgraded and 540 rpm & Cat 1 became the popular choice for small implements.
- Dave