With many cars having been rebuild at least once now, the distance between the front and the back of the car may well not be as Triumph intended.

Before purchasing it might be useful to measure your car. The distance fore and aft between the captive nuts on the roof panel, is 760mm. Bear in mind that the captive nuts in our fibreglass centre panels are floating, being a 5/16"UNF version of the ¼"UNF nuts found around many areas of TR4-5 where a square nut floats about in a pressed steel square shell slightly larger than the nut thus allowing for a small amount of dimensional flexibility. There are roof panels on the market with M8 rigidly mounted nuts which render the roof panel virtually useless.

Also bear in mind that the holes in the windscreen frame and the backlight frame through which the bolts pass are much larger than 5/16" too so more leeway is available there too. Also the backlight frame can be moved fore and aft a little and the rake of the windscreen frame can be altered slightly.