Here is a link that should answer your questions regarding checking boost.http://hsb.baylor.edu/html/easley/autofaqs/boostchk.htm
This one
http://hsb.baylor.edu/html/easley/autofaqs/wgate.htm tells about identifying brand of charger (KKK/Garrett) and adjusting pressure. I found out the brand name of mine accidentally by removing the horn that goes from the airfilter housing to the turbo inlet. At this point I could see the letters "KKK" on the turbo. I must say I was surprised at the size of the blades...much smaller than I thought.
Good luck and be careful..."them things aint cheap"
-Larry
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03/83 300D
07/73 280