I have a Y block with a foromatic tranny.....not sure of the year because its in a 36 ford pickup when I bought it and the previous owner was clueless.

anyway the last time I rebuilt the engine I thought i had a rod knocking and it turned out to be the flex plate slipping.  Lately it has been making the same noise only when its cold or on cold start ups.........and now the starter won't turn over the engine and I hear this banging and locking sound when I try to turn it over. I even bought a new battery thinking that was the problem and hooked up jumpers and ran two batteries to it.......but it just keeps laboring and then locking up on a bang or loud clank......My friend told me its sounds like the starter but I don't want to replace that if the flex plate is going to do it again the the new starter .......Help!