Thanks a lot Mike, so four of these I assume, that's a great little trick to know!

Will get these ordered up now, I've already ordered the rest.

Tosh, thanks, it clarifies what I've ordered, and had no idea the bolts were different, mind you if you'd seen the beam I dismantled there was nothing left of the fixings to properly identify them. I have a very good used set of carrier bolts so will be ok for those at the moment, but might try and get some just to see if it's possible.