ford gpa g504

I am interested in what the bolt length is for the bolt that holds the PTO onto the back of the transfer case. The manuals all say 3/8-16 x 3”. That seems excessive! My PTO is installed with its original bolts and it is not easy to remove one to check the length or what would be required. Does anyone have an original bolt hanging around that can get a measurement. Also, would a shorter bolt work?
Thank you,
Donovan.