[Alan Roehrich]

Dwight, most of the 454 trucks (3/4 ton and up) we had in the shop, Suburbans included, had 1/2" lines. Not all did though, you're right. Yes, the fuel lines do run outside the frame, high on the side and on the top in places. They were out there to keep them cool, and keep them away from shrapnel from failed drive shafts and such.

Now that you mention in though, around here, most every C/K 20 series truck was a "C6P" truck, which had a heaver GVWR. The dealers just ordered them that way. But you could get the C/K 20 series without that option, and those did not have all the heavy duty equipment. A "C6P" truck was just about a 1 ton truck. I'm pretty sure that the few trucks we had through the shop that did not have those lines were not "C6P" trucks, that would explain it.