More 1985 300DT Questions for you pros....

[wordmanjay]

Continuing to bring the maintenance up on my '85 300DT. I've run into a few more questions. Here goes:
1. What is the correct name of the 3-pronged switch on top of my valve cover that is activated by my accelerator mechanism?
2. Where can I get one of those 3-pronged switches?
3. Smog hose? What is the correct name of the hard plastic tube that connects my "breather hose elbow"(coming from the top of the air case) to the rubber elbow coming out of the top of my valve cover.
4. Where can I get one of these "hard plastic tubes"? I can only find a Cali type online. Mine is a "fed" type- plain curved hard plastic tube.

Diagnostic question:
I'm getting a lot of oil coming through that "hard plastic tube" and making a bit of a mess inside my air filter.
My mechanic (a non-diesel guy) said that too much oil coming back through that tube indicated a faulty PCV valve. Hmmmm.
Previously, someone here suggested I take the top off of the little cannister inside of the air case and seal it back down with some sealer-he said that may prevent oil from soiling my air filter. Hmmmmm.
1. Does that 3-way switch have anything to do with this? It's cracked and barely hanging onto the male end of the connectors.
2. Does this engine have a PCV valve?
I kinda need some elaboration on this topic.
As a side note, just on the outside chance it's related- this car was hit in the back end and the fuel spout area got crunched(enough that the fuel door is permanently open). The vacuum issues include no power door locks, faulty opening and closing of vents, and manual engine shutoff (under the hood). Also, the glowplug light on the dash doesn't come on anymore(that may be a separate issue).

Please help. I'm sure you will. You always do.
Thanks.
Jay