About the only 3 rail producer of brass that I’m aware of is 3rd Rail, and I believe they are mostly steam.
I’m thinking about purchasing a brass diesel kit, but in order to power it for 3-rails, I’d need a 3-rail power chassis (motor, wheels, rollers, truckframe). These are sold by Northwest Shortlines and several other firms for 2 rail O, but do any toy train companies market these for 3-rail? I realize I could purchase a diesel and simply swap the shell out but I’m specifically wondering if power chassis for 3-rail trains are sold.
Thanks.