Thanks, John. The battery site didn't include that Molex. I found them, 2/3AA NiMH, 800 mah on another site, from China, for $3 each in lots of 8, with wire leads. I'll solder the old connectors to these wires.
My 2.4-volt PS2 batteries are 6-10 years old, so it's probably time to change. I have about 18 of these locos, so alternatives to a battery is not economically feasible.
I note that the 2/3 AA are 700-800 mah, depending on source, which is the same rating the the full-size NiCad AA's MTH used to use.