Hello,
We a have a MDT 30 plymouth with diesel fuel cooled twin disc torque converter. The question at hand though is the transmission. There are no nameplates. In the manual from 1964 it says its a Fate Root Heath model HL11 mark on it. It also says in the manual to use sae90 gear oil in the back and C1 transmission fluid in the front.
WW Williams told us to use hydraulic fluid in the front and and 10w30 in the back. We did have a bad experience with them also.
What fluid is the proper fluid to use?

If the transmission is indeed the one that it was built with, go with what the manual says, as there is a big difference in the characteristics of the factory specs and what WW Williams is telling you. If you are having issues with it using what the latter recommended, then I'd flush it out and put the factory spec fluid in (both of which have a higher viscosity than what Williams told you). Now if it has been replaced, rebuilt or modified that's a whole other can of worms.

Thank you,
From alk the paperwork the original owner gave us it looks like it as been the original transmission rebuilt by plymouth once and us once. I have been told within the hour that the clutch plates were sticking supposedly by williams due to fact that the transmission was filled with wrong fluid or over filled.
Nothing like getting a project after the fact, but that is what makes this stuff fun.

Todd

If you have a Twin Disc torque converter use only fluid rated for it. There is a special formulation and reg Hyd fluid that you can buy at the farm store wont work. Any of your bulk fuel people who sell fluids to the construction industry will have what you want. You will need to flush the system before you put the new fluid in.

Thanks,
The twin disc torque converter is cooled and or lubed by the diesel fuel on our engine.

Todd