[DaleHCook]

I'm not sure if the 144B had the 4 pin spkr plug on the back of the chassis. Some of the larger sets didn't like the early 16B's. They were wired straight into the chassis with no plug. Bit of a hassle to service and it's not noted on the diagram.

If the 144B is largely the same as the 144 I would expect a speaker plug because the 144 print has Xs imposed on the three leads going to the OT primary and the field coil (a convention sometimes used to designate a speaker plug and socket), and the parts list specifies a speaker socket.