Hi David
When I was restoring my 1942 MB Willys Jeep and doing research on the vehicle, I heard or read somewhere that in normal active service areas the life span of a jeep was 6 months. However the life span of a Jeep on "D-Day" it was down to 10 hours. I have heard similar stories from others but I can't confirm how accurate these figures are.
Cheers
Tony