Grizzle
Lil-Rokslider
I bought a cheap propane burner for this job and just use a stock pot with it.
That's how everyone I know does it with great results.
Reading this thread has me shaking my head wondering why everyone is complicating it so much. I mean these units look like they would work great but seem like way more effort than needed. Also sounds like guys are cooking them way to long. Clean the skull up best you can before simmering it then Powerwash it with a good pressure washer and your done in a couple hours start to finish. The better you are with the knife work the faster it goes but simmering for 10 hours is beyond unnecessary.