hey guys. I got around to tearing down my duraspark donor distributor and this is what i found for advance slots. 16L(or 18L couldnt read it) and 21L. Now, from what i have read, the those are to big. willgive me to much advance.  what distributors are the best canidates for the 10L and 13l advances? read somewhere that the big blocks are more apt to have the 10L and 13L advance slots. is this true?