Can you install a five speed trans in a flathead Ford car?

The stock manual transmissions for the flathead give satisfactory performance under normal driving conditions, but will not survive hard launches reliably even with stock engines. Not to worry since there are several options for upgrading the transmission both manual and automatic. Five speed (including overdrive) manual transmissions such as the Borg-Warner T-5 or Tremec work great because they are compact and efficient and several adapters are available. The Ford C-4 automatic (three speed) works well for the same reasons. The C-4 is the only automatic that does not usually require metal cutting to install in an early Ford. An add-on aftermarket unit is required if overdrive is desired. There are also adapters for almost any EOD or AOD transmission but since these units are large they often require major surgery to install and they use significant horsepower just to drive the transmission.