If the T is fibreglass then the aerial wont work very well as it needs a ground plane. Some self adhesive metalic pads or a sheet of ali underneath the panel often helpsI have mounted an aerial underneath some of my cars. with varied results.
My high escort had a normal one just mouted of the floor near the back and worked ok.
Also did one a lowered mini, that was a short rubber one and worked really well, have the same on the T but it dosnt work!