Again -
FOMOCO used TYPE A and TYPE A SUFFIX A same and/or similar to GM until FOMOCO began formulating there own fluids (used different friction materials than GM) beginning in 1959.
TYPE F was not introduced until the release of the 1968 model year. The friction material(s) was again changed. TYPE F will give a more firm shift used in friction materials it was not designed to be used with (good and/or bad results). It can be a plus or a negative as it depends on how an owner wants the car car to perform.
This car is a cream-puff and I would imagine the owner wants a nice easy shift with no delay between ranges. TYPE F ain't gonna get it.
IMO, the application needs an early DEXRON blend. A Syn will allow much less friction but may also not lubricate properly.
The use of aftermarket fluids is a crap-shoot. If GM still offers an early DEXRON or there is a refiner that blends to the exact period specification(s) then that is what should be considered for use.
And then there is the possibility of the trans never being serviced as the builder suggested and the new detergents wipes out the trans.
If the owner of that MERC took as good care of his wife as the car, she should have been a dead knock-out...
