dandaman

I am 64 years old and have been messing with old cars and trucks all my life, but this one has me stumped. I have a 86 f 150 with a light blue interior, purchased it from the original owners widow. Here's the question has anyone ever experienced a brown crud, hard crud, on the hard vinyl interior surfaces of these trucks? Its not on the dash at all. Its not everywhere and it does not cover even the same part over its entire surface. I have tried every thing I know to remove it, like 409 and crud cutter, but the only way to remove it is to scrape it off. Now when you scrape it off it also takes the grain off the part, it makes it smooth. The parts are perfect other than that. Two questions, can the grain be put back on then repainted to original? Anyone had any luck getting this crud off the parts. another question, who make the best rattle can paint that correct color for these trucks? Thanks Dan