this is going to sound real stupid but how much trans fluid do you put in a c4 auto. trans

 

Off hand, I would say to make sure it's at least to the minimum mark on the dipstick. If you are starting from scratch, for a 66 it's 7 3/4 quarts for the I6 version, 8 3/4 for a 289. Now check the dip stick. Any more, I wouild look for a puddle, any less, you may still have some in the torque converter.
Jim

 

Yeah, don't forget that the torque converter holds about 5 quarts and the tranny itself holds about 5 1/2. If you didn't drain the converter, then put in about 4 quarts and check it after you have run the engine and put it in gear. If it is still low, then add. You may want to spin the engine over until the drain on the torque converter is visible after the inspection plate has been taken off. If there is no drain on the converter, then that is another thread and a whole lot more explanation in how to get that old fluid out of the converter.