Seems like one of the accepted CCKW jacks is the Walker 925. But there are several that have that number. Below are two Walker 925s. Note the tags.
Whats odd is that TM9-801 April 1944 is the only TM9-801 to have a picture of the jack. The April 43 version does not.
Also, it seems that BOTH series C and D may have been used. If you look at the APRIL 1944 TM9 on page 23 the linkage is the flat stamped type (Series D), and on page 402 it shows another jack with the cast linkage (Series C). Both jacks in the TM seem to have different decals.
Series C (3 1/2 tons)
Series D (3 tons)