I would recommend pulling all the carpet and mats and exposing as much of the vacuum system as possible, pick a nice sunny day with no interruptions and go to it. My issue was the vac. reservoir, which I patched at the inlet with silicone, and the fuel door lock pod. Not sure if yr 78 has the fuel door pod. I just plugged it and took it out of the loop. Not too many people can even figure out how to open the fuel filler flap anyway.

__________________
1985 300D Gretchen (Astral Silver) 220k
1983 240D 4-speed Evelyn (Orient Red) 203k


TANSTAAFL