Rob have PM'd you as well, thought I'd post too:
It's been a while since I put the unions in the tank (I've check it was 2006!!
http://www.msportster.co.uk/2006/05/29/pump-filters/)
The output at the bottom is 12mm pipe to the first filter. The output from the first filter to the pump is 8mm.
Here's a close up of the union in the vent at the top:
This is the pump / filter layout:
You can see he return feed to the tank in this pic:
I'm using one of these for the fuel tank breather / vent:
http://www.merlinmotorsport.co.uk/FU...duct_info.html