Auto Parts: transmission gasket info, chrysler transmissions, borg warner

Question
hi,i have a 68 amx 390 auto.my trans pan is leaking need to change gasket.i got a gasket i thought was for a m12 but it does not match pattern of my trans pan. the gasket is square except for  one corner which steps out about half inch or so on one corner.my trans on same corner goes in about half inch.wandering if i got wrong gasket or my trans is not a m12 please advise thanks

Answer
    Well, when I look the part up I get a gasket that sounds like your description of the transmission pan.  So, it sounds like you need to buy Fram's filter kit #FT1039A (comes with two different gaskets).  This is a Chrysler transmission.  AMC used it behind their biggest engines because the Borg-Warner wasn't up to the job.  Jaguar switched to the GM TH400 in the late '70s for the same reason.  It is never a good idea to just change the gasket; always change the filter along with it.  This is especially important with Chrysler transmissions; they are sensitive to lowered hydraulic pressure which can result from a clogged filter.