good idea for you to say exactly what bike you have and (preferably) post a picture, then there is no "working out" to get wrong, there are lots of (very) slightly different types for all models from 1968 twin to 1987 triple and everything in between,
so its a triple
might be a 3CL
might be a 1200, 1200T, 1200TS possibly a 1200 Anniversary,
might even be stock or modified, of any of the above.
be as specific as you can, like they always says, very annoyingly at the factors trade counter when you ask for as an example, "3 metres of 7mm copper cored silicone HT lead please" the answer is always "whats it for mate?"
CLEM
ps I spoke to a bloke the other day who thought that all three triple front pipes were the same item and no differing between 180 and 120 still all the same. All three front pipes differ, and also between 120/180 so that is six part numbers, maybe more for all I know.