I'm finding the 5/16 ones pretty easy, not so much the 3/8 ones so far...
Lots of good part numbers from Prof Fate, but so far no onne that actually has them in stock..
I just remembered one issue I had with the van. When the fuel level in the tank was low the engine would run rough.
I closed off the return line to the tank, and the problem went away. Hopefully you won't see that problem!