The rest of the story: I did a bunch of searching on the web, and found out the story behind the vacuum line filter. Apparently GM had a bunch of brake booster warranty issues and failed parts problems in the early and mid seventies. It seems gasoline fumes were gassing off from the intake manifold and getting into the brake booster, damaging the booster diaphragm, causing brake assist problems. GM's "cure" for this was a charcoal infused filter between the manifold and the brake booster. The charcoal was to absorb the gas fumes until the next engine operation when the fumes would be pulled back into the engine. From a few peoples' comments, GM recommended that this charcoal filter be replaced every year. I doubt if many people did that, but I do wonder if the filter would disintegrate with age and vibration, resulting in a filter and hose filled with charcoal dust (see where I'm going here?). My earlier observation that my booster hose was full of plastic powder was most likely charcoal from the disintegrating filter internals. From other info it appears that this filter was used from 1978 to 1984 model years. (I'm using a 1984 design booster, so I had copied the vacuum details.) So, while I still have the '84 design booster on my car, it's not an '84 vintage piece, so I'm wondering/hoping this ten year old unit is built with whatever improved material is in later boosters that are not vulnerable to gas fume damage. I think I'm going to forgo purchasing another charcoal filter, and just see how things go.
If I had heard about this issue thirty years ago it would have surely saved me time and aggravation this past month.
