On another note, these two CF-7s just got through pulling 101 40-foot cars weighing 6 ounces each, and this was around two 25" radius 90 degree curves! There was a touch of wheel slippage, but they kicked butt. Now, backing the cars up was an issue, more slippage and some of the cars on the first curve would derail. I guess that is alot of pressure to push them around the curves versus pulling them.
As it is now, I can only mix a "female" loco with a "male" loco. Not very politically correct.
It just dawned on me that I should have female plugs in all the locos, and then have wires with male plugs on both ends, then any loco could be attached to any other.