Series 3 Truck Top

Gents (newbie - so be polite)
Is the truck top a one size fits all?
I guess I'm at least going to have to remove the seatbelt bar to make room for one.

Truck cab will fit LWB or SWB but for the short you also need the filler panel as the behind seat bulkhead is further forward.
Seat belt bar ?

Yes I have a bar that looks like a mini roll bar which carries the seat belt straps from the inertia blocks on the bulkhead to shoulder height - I thought every canvas top would have one of these. This bar looks like it would be in the way of the truck top. Prob
Em is the truck top I have has no seat belt mountings.

There are seat belt brackets which fit into the side of the truck cab to connect the seat belts to - if the seat belt bar that you're talking about is the same as the one I have on my soft top (can just about see it in the attached photo), then it won't fit with a truck cab I'm afraid - part numbers for brackets are I think part numbers are 395246 but basically it's a bit of C-section with end plates that runs from top to bottom behind the leading edge of the truck cab with a bit of plate on the face with a hole in it to take the upper seatbelt mounting - if using truck cab on a SWB Series then you will need a horizontal piller plate to close the gap between the bottom of the cab and the top of the bulkhead behind the seats to the tub