How do you mean clogged? I know that this is taking away from the main thrust of the thread, but there is a filter on the bottom of that canister. This will not be something that causes fuel to drip into the primaries, whether it is clogged or not. You can find a complete downloadable service manual for your truck here:
http://67-72chevytrucks.com/vboard/showthread.php?t=558016&highlight=hatzie"]http://67-72chevytrucks.com/vboard/showthread.php?t=558016&highlight=hatzie
Just copy and paste that in a new tab.
