I think on some vehicles that they did. I'm certain it was used on the ends. but it's been thirty years since those vehicles were new and I've long since retired.
Again! It was inexpensive. Most of the manufacturers dabbled with silicone. It was found that the use of these products caused sensor failures, particularly O2 sensors, when used in repair situations where the product was not allowed to completely cure before the vehicle was returned to service. A problem that still exists to some extent today.
NOTE: This was not a problem with new vehicles when built because the engines were assembled in separate facilities and shipped to the final assembly plants. The silicone had time to cure before the engine was actually started and run.
