I bought Raybestos,mc36221dual mc , that was recommended to replace
my single mc. Well this has turned into a nightmare , because my 63 Dart has 3/16" brake lines , and the new mc has much larger ports, and I can't find adapters. Is there a mc I should be using that the lines on my car will thead into without a hassle , thanks in advance,Jim.

3/16" is the correct line diameter for both early and late cars. You cannot just connect the original lines to the dual master cylinder; you must make new lines from the new master cylinder to the new distribution block you'll need,
which can be had used from any A-body with 4-wheel drums, '67-up, but probably easiest and safest to get it new from Inline Tube for $35. You'll need to run dual hardlines from the new master to the splitter block. Be sure to bend at least one fully-circular loop in each of them to let them flex. Steel line is standard and is a pain to work with; Cunifer is a lot easier (and better).

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