does anyone know which way the coned washer/spacer goes in the USD forks on a beta rev 3..2000.it sits behind oil seal

Same way as you took it out. You likely are not making it taller. If that helps. Remember the seal holder actually floats.

thanks for ya help..only problem is I cant remember which way it came out.. and domt want to force it as dont want t damage new seals

The flat side to the bottom of the holder. I usually put the fork body in a vice (aluminum jaws, not tight ) with the seal holder just resting on the top of the jaws so the holder does not move while installing seals. Hope this helps.