ok, as sierra parts are like rocking horse poo to get hold of, Im looking for alternatives

what cars have rear hubs that bolt up like a sierra has?

I can get BMW diffs etc cheap enough and prepared to mix and match no problems, but looking for an easy option for the outboard mounting.

Im planning on using probably a BMW diff as I can get the close to the 3:1 ratio quite easily that my bike engine wants, but the quick look Ive had appears to show that the rear arm and hub etc look like one peiece?

You can buy alloy Sierra hub carriers at quite reasonable prices, there was a recent thread that listed some suppliers.

http://www.locostbuilders.co.uk/viewthread.php?tid=165392

Did you want Sierra drum or disc bearing carriers?

I have some drum ones with the drive flange machined down to suite the RD/Wilwood disc handbrake caliper if you want them?