I just submitted the OMI for the D8 14A & 15A tractor to the library. Parts of the OMI for the 15A about the torque converter is an interesting read.
Caterpillar engineers were trying to introduce torque converters in the D8 15A  & D9 19A tractors. The D8s & D9s still had dry steering clutches and brakes so where they going to get the fluid necessary for the torque converter and keep that fluid cool? Their answer was to utilize the diesel fuel in the fuel tank for the torque converter! The torque converters also had a design that allowed a slight fluid leak. The customers who bought new D8 15As & the D9 19As were told that it was normal for their tractors to drip 10 drops of diesel fuel per minute on the ground! They were also told not operate their tractors low on fuel especially in hot weather!
Here's a sample,
Craig
 

 

 

The 15A had a clutch, torque converter and a 3-speed manual transmission.
The 46A was the first D8 with a diesel torque and a power shift transmission.
Bob

We've had this discussion before.....
Cat cheaped out and left the oil circulation portion of the Twin-Disc system out.
 
 
 
 

Thanks for correcting me Bob. I was in a rush and remembered a statement that those tractors were the precursors to the powershift tractors. 
I corrected my post.
Craig

Near as I can tell it was the same as Allis had.