All the 4l60e transmissions in all the makes and models of vehicles including Chevrolet, Pontiac, Oldsmobile and the ISUZU vehicles take the DEXRON III type transmission fluid.
As long as you use the DEXRON III transmission fluid you'll be good to go and make sure you do use the correct transmission fluid because the wrong transmission fluid can lead to loss of lubrication and transmission damage and transmission failure.
The 4l60e also takes around 4 quarts of the DEXRON III transmission fluid if you drained the transmission pan but if you drained the torque converter as well as the 4l60e transmission pan then you'll need 6 quarts.
But if you just dropped the transmission pan then you'll need only 4 quarts of the DEXRON III transmission fluid to refill the transmission.