66 galaxie transmission fluid

I have a 66 galaxie 500. Haven't had it long. It needs a quart of transmission fluid. (It doesn't slip..tranny seems to be fine....only a surge....it's an automatic) I'm not 100% sure type f is in there however there is indication from a service sheet in glove compartment that a quart of type f was added before. What happens if there is type f in there and some other type (like mercon)?

On another note, the car has a pretty pronounced surge. I checked the distributor, timing,sparks etc. and all was fine. I'm thinking carburetor but I was under the impression when I "acquired" the vehicle that a carb. rebuild had just been done.

type f is the proper fluid for that trans did you check the dwell on the points it will cause rough idle and look down the throut of carb see if it dripping fuel from nozzel it could be floet adjustment . if you have any ? of type of fluid change it and starte from scatch some time any other fluid will cause tran to shift hard ford in that day use the clutches for grip were gm useed the fluid for friction between the clutches

Welcome to Automotive Forums. Use Ford type F. There are some other tranny fluids around that are compatible with Ford type F such as Pennzoil, Amsoil and Royal purple. Type F isn't compatible with Mercon. There's no way to tell what kind of fluid is in the tranny. Use Ford type F.