If anybody is interested in tank transmissions and steering systems i have written a very long and detailed article about the Cross Drive CD-850 transmission found in Patton tanks and also went into explaining the Merritt Brown system through Z51R from Centurion and TN.12 from Chieftain and comparing it to the Cross Drive series. It is a bit long around 78000 words and 450 pages but if anybody is interested on such topic here is the link below.
Patton Tanks Transmission and Steering Unit GM Allison CD-850 Explained and Compared With Centurion’s Merritt Brown Z51R – Tank Automotives (wordpress.com)