i have rebuilt two engine and used this manual, It is a modern reprint of many of the original manuals
The Complete WW2 Military Jeep Manual by Us Army, Paperback,
( easy to spot is has a three colour cover with a blue band at the top, green in the middle and red at the bottom)
Desciption from the listing "Comprehensive manual containing full information on how to maintain and overhaul the Ford and Willys Jeeps manufactured during WW2. Includes TM9-803, TM9-1803A, TM9-1803B, etc."
currently on ebay from various sellers for about £20, well worth it in my opinion