It will hold 6 quarts in the transmission, two or more in the converter and depending on the size of cooler, around two for that. Most take 10 to 12 quarts to fill the system from bone dry.
I am assuming that the driveshaft yoke is in good condition and installed, the rear seal is ok and any tailshaft housing gaskets are in good shape. If yes to all, then check for cracks.
