Yep, sure looks to be for the T-3.
$20 was a great deal, too.
73DG
I noticed the the T-368C model used a single 115 vac primary and 6336 vct secondary.
I don't have a T368 but at that price I couldn't pass it up, although my back didn't like it and it's still on the right front floor of the truck.
I'll have to live to be 100 to catch up on all the projects in line here, including a Gates BC-1J and a BC-610E, before I get to building a big one from scratch but I am accumulating parts when they show up. I've got lots of plate iron but I'm short a modulation reactor.
Thanks,
Greg