Stock is 3/8" nylon tube (portions of the fuel supply line are metal but you could replace with nylon). EVAP purge line is all 3/8" nylon. NAPA sells repair kits that can patch your lines to get you home. Would be good to find out if your lines were upgraded/replaced with the swap... I don't know about the 5.3 fuel rail fittings.
The fuel tank has the evap and fuel lines terminate at about the transmission cross member with 3/8 quick connect fittings. From the tank, the fuel line is male and the evap is female. NAPA also sells repair kits with compatible fittings; they include some tubing, the quick connect fitting, and a brass barb coupler to tie back into the original line.
Last edited by rockystock; 07-18-2018 at 05:28 PM.