On my sons 400 I use a stock Mopar B block dist thas most likely from about as mid 70's 400 I just recurved it with Mr Gaskets springs as set the amount of advance I wanted in it. It has benn running good in his car since 1997. On my 63 I picked up a Mallory dist for a good price and its a nice unit with adjustable advance and spring tension. Its been working flawless in my 63 since 2006. Ron