I've always been interested in Opel GTs but know little about them. I'm interesting in "original" condition cars and eventually will buy one. What was available as far as options? Whats desireable? What to avoid? I have a line on a clean '72 from California that is incredibly origninal and rust free! Runs too! But, its an automatic! How hard to convert to manual? What would be the transmision to use?