Got a GP300 off of ebay( I know= I know)

The radio works fine but the short fat stubby about say 3 inches or so long really doesnt seem to fit the radio threads just right.
This antenae has a green bottom but it also looks like it needs a pin in the radio to mate up into the antenae to contact the antenaes insides.
The antenae screws perfectly onto a GTX 800 portable and if i use a stubby i know fits the GP300 it screws perfectly into the GP300 and seems to work better than the Green center pin fed antenae.
Anybody got an idea as to what freq and radio this green center pin fed antenae is for ?
It has no markings on it other tha Motorola.
Thank You
Satelite