Hi Brian K. here, I took a quick measurement of the firewall to engine block line and it's about 7 inches long. I dont have access to my inside line but the Chevrolet service bullentin says that dealers are to take off the junction, drill the hole bigger (1/2 inch in size) use the line thats inside the car to go to the block (it supposed to be long enough) and add the rubber grommet part number 3906193. Remember this is for people bringing their cars back to the dealer with oil leaks, that how GM told the dealer to fix it. The bullentin says effective June 5, 1967 the 2 piece design will be replaced to this one piece set up in production cars. My 11E build 67 RSSS has this set up owned since 1988, my original lines are white translucet in color. The current repops are black, I've found a good replacement from Auto Meter part number 990023 which looks and functions like original. Glad to help, I'm using my dads account here sorry for any confusion. Sincerely Brian Kotula
Bob