I assume you mean the O scale ones (#804 & #805) ??
Any of the usual US outline suppliers should be able to get them, but some will keep them in stock anyway.
Try M.G. Sharps at Sheffield:-
http://www.kato-unitrack.co.uk/kadee-o- ... 919-0.html
Model Junction don't list O scale but will order, I'm sure;
http://www.modeljunction.info/estore/in ... rers_id=46
Then there's The Sidings Tamworth (but not the Midlands Tamworth!!) who also list them in stock...
http://www.thesidingstamworth.com/stock ... 33&MfID=18
There isn't the vast variety of different types that there are in HO; O scale is much more standardised. The difference in the two part No.s is that one is in plastic and the other metal !!
The Dark Side does have it's uses... even on a Western Region Forum..!! :lol: