ATF question (confused!!)

1983 F100, 300 cid,  AOD, Haynes lists 1980-dexronII--1981 on Mercon. I read on another forum that they were the same, Ford just changed the name for marketing purposes.

Please---what is the correct fluid, I need to change filter/fluid, and don't want to chance ruining anything.
Dex/merc-mercon LV, or Dex/Merc, both are Valvoline products, the later being $4 cheaper. LV is low viscosity, do I need LV, or is the Dex/Merc OK?

Other than dirty fluid, the trans seems OK.

Thanks, Bill..old Ford driving an old Ford..(BTW, Gary, I have you by about 10)

Bill - I feel so much younger now.  Thanks!  

As for lubricants, we have a page here: Specifications/Lubricant Specifications.  This info is a melding of several owner's manuals, and it says this, with the bolding being mine:

Automatic Transmission — C6, Automatic Overdrive:  Motorcraft DEXRON® II Automatic Transmission Fluid

But even better, there's a link to this writeup on Hemmings that has these specific comments re Fords:

Ford first produced its own transmission fluid formulation in 1967, referred to as Type F or Type FA. The name comes from Ford’s specification number for the fluid, ESW M2C33-F. This fluid was used in all Ford transmissions until 1977 and most Ford transmissions until 1980.

The development of the C5 transmission in 1981 brought a new specification called Type H, named after the specification ESP M2C166-H. About the same time, Ford C6 transmissions upgraded to a new formulation, ESW M2C138-CJ or Type CJ. These transmissions cannot use Type F/FA; however, Dexron II could be substituted. Type H eventually was reformulated and received anti-shudder additives. It was then renamed Mercon, and it was an acceptable retrofit for both Type H and Type CJ and became the new Ford standard fluid from 1987-2007.

Mercon V was introduced in 2008 and supersedes any requirements for H, CJ or Mercon. It does not replace Type F or Type FA, but is often marketed in retail establishments now as Dexron III/Mercon V and takes the place of any previous non-Type F/FA requirements.

Mercon SP was prevalent in 2005-2007 six-speed automatics and has additional additives over Mercon V. SP can be substituted in any Mercon V recommendation. Ford also produced its own Mercon CVT fluid from 2005-2007; however, all aftermarket CVT-specific fluids meet the Ford requirement, no matter who the manufacturer.

The year 2008 saw the release of Mercon LV, a synthetic-based fluid that is not compatible with any previous Mercon specifications. Transmissions requiring LV include the rear-wheel-drive Ford 5R110 Torque Shift and 4R75/WE transmissions, as well as the front-wheel-drive 4F27E, AW ECVT, 6F50/55N and the 6F35N.

Bottom Line: Dexron/Mercon, with V being good and SP being better.  But not LV.

I will throw some more on this Type F is a petroleum based fluid with a friction additive. Dexron is a synthetic developed by GM for their transmissions and was designed to make the shifts smoother (read softer).

A number of manufacturers used Dexron and Dexron II as OEM, Mercedes-Benz among them. FWIW, generally any older automatic (like and FMX or C4) that called for Type A can also use Type F with no problems except maybe a little crisper shift. I used to use Type F in the early Mercedes-Benz transmissions, the one called a "16 bolt pan" model (pan isn't as big as a C4 pan) as that one called for Type A as they were notoriously finicky due to no band adjustments, using reaction valves to help time upshifts and downshifts and would slip horribly if everything wasn't perfect, then they jerked almost as badly as the single coupling Hydra-Matics.

A lot of the changes were due to (a) wanting to get away from Petroleum based fluid (b) trying to balance shift quality vs longevity (c) higher temperatures from catalytic converters and (d) higher temperatures on FWD vehicles.