Both old and newer Tbolts used a 4 pin connector. The probable reason yours has a 5 pin is because they were used on many late 50's and early 60's CB transceivers as mike connectors and so previous owner probably cannibalized the chassis connector from a transceiver and the plug from a mike cable.
I believe the part # for the 5 pin plug is Amphenol 91MPM5L so probably the 4 pin is Amphenol 91MPM4L.
It might be less aggravating to just go to Radio Shack and pick up one each of these. The hole diameter should be fairly close.