Hi Jim4,

The green dot was Fords "dual range" feature, in 1966 it didn't matter which transmission you had; FX, MX, C4 or C6 they were all green dot and Ford refers to them as all Cruise-O-Matics in different literature. Hence the large confusion for some. The FX and MX were Borg Warner designed transmissions from long earlier. Ford came out with the C4 in 1964 and the C6 in 1966. So for roughly 1 year only the C6 was a dual range (1966). After '66 Ford went to select shift pattern (PRND2L).

On the C6, you can replace the valve body (certain year ranges only work) for either the dual range or select shift pattern.

 

The older MXs were dual range but used a black dot.

 

Thanks Desert,
What is "dual range" and will it be hard to find parts to rebuild my green dot transmission? does dual range mean that I can manually shift and automatically shift the trans? Any problems with this transmission? Tell me more about changing the fluid if you can. Something about new fluid messing up the seals? Should I change half the fluid? and then again later?

 

Hello JIM4,

Just like galax-z said, the green dot is the same as regular drive in that it shifts 1-2-3. The closed dot on your floor shifter starts the trans in second. So it's 2-3, it just skips first gear. Both ranges are automatic, no manual shifting.

About parts, depends on which transmission you have. Being a '66 7 litre, it will have either the MX or C6. They are completely different transmissions. The MX being a Borg Warner is harder to find parts for. The C6 is aftermarket rich in parts. I believe the door tag should have the info on what trans is in there, or just have a look underneath. If the trans looks all aluminum it's a C6 or if it has a cast iron centre section it's an MX. Also I believe the pan on the MX is pretty much rectangular, while the C6 has a noticeable notched corner.

I can speak for the C6 in that the valve bodies are interchangeable (withing reason of years) and the valve body is what makes it a "dual range" (aka green dot) trans versus a select shift trans (PRND2L). The rest of the C6 is the same.

About changing fluid. If the trans has never been serviced (rebuilt) chances are the seals are hard or getting hard. After all it's 50 years old. Changing the fluid with fresh oil might in the case of old seals cause them to leak and the trans will fail in short order. In the case of the one '66 I changed, it was right after I changed the oil. No more forward gears. To be fair the car sat in a field for 40 years and it was probably the original fluid from '66 in there to begin with. The car only had 30K miles on it. Weird part is that it shifted fine just the fluid was nasty. Remember ATF is detergent oil that cleans. So good in fact it cleans the gunk keeping the crusty seals pressurized in the trans

I look at it like this, best to know now then on a road far away from the house. I realize most folks wouldn't try to pull the trans on the floor of a garage or driveway then take it all apart to clean and change seals, but it is peace of mind having it done either by the owner or a shop. If you do it yourself, the seal kit for a C6 is around 40 dollars, just it's all your labour.

Cheers..

 

the duel range means in green dot it starts in 1st. D starts in 2nd- good for slick conditions