mrfixit
Chief Chaotic Engineer
Oh... heat riser tube should be between your air cleaner horn/snout/intake and the exhaust manifold directly beneath it. When your truck was made, they were constructed in much the same way as that "cardboard hose" on your charcoal canister, except about 2" in diameter, +/_. Nowadays, the replacement looks more akin to a dryer vent hose, just smaller.