I'm having to go through the same issue currently on my 72 C10 (PO ripped it out). I've found some parts through vendors (Inline Tube, LMC, Classic Ind, etc), but I've gotten a lot of the small/hard to find parts through guys parting trucks here on the board. Not sure how much this helps, but here's a diagram in the LMC catalog for reference -
http://www.lmctruck.com/icatalog/ca/full.aspx?Page=92