These are the black ones at the same vendor:
The only thing I don't like about them is they're hard to balance. The hubs are either lopsided or the holes are off-center. That's why I switched to MA.
I'm using Glowplugboy 24% nitro. I add castor to bring it up to 20% oil so that drops the nitro a bit. All of my other Tee Dees and my 3 Big Migs run good with this fuel. The Satan is in the hangar now with a 5-1/4x3 MA awaiting the next flight. And I have a couple of 5x3s and a black Cox 5x4 in the flight box too.
This engine has a funny crease in the crankcase. It was like this when I got it, and could be causing a friction problem..If it gives me any more trouble, I'll swap it with another Tee Dee that I know runs good.