Drove my Malibu finally this weekend..the TH 400 sucks!! short shifts..never lets the motor wind up..and the 3 31 gears dnt help at all

..considering a newer electronic 4 speed auto..I can still get it installed before the season starts..but which one..700R4 or 4L60/80..needs to be solid as I plan on upgrading the motor at some time. Thanks
ALbert