Tom,

The harness does indeed go "through" the firewall, but it all comes apart. There are two rubber seals going entirely across the engine bay, one at the false firewall and one just behind it. Both pull off, and then you need to take apart the plastic shrouding under the monowiper and over the air intake for the HVAC. From foggy memory, there are a couple of phillips head screws hidden deep in the crack of the plastic air duct.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC