Motors Manual, distributor cap firing order Mystery

[symplesymonsezzz]

Hi. I have a 66 6 cyl inline 250 from a truck. My ? is whats going on with my firing order in my dist.cap. The book shows the following. With the "R" facing the firewall and the srcew near touching the block. To the right of the screw is #4 followed by #1 #5 #3 #6 #2 as seen in the book. This is not what I have and will not run, I tried this. This is what runs the car and I put 600 miles on it last summer. Going clockwise from the screw #1 #5 #3 #6 #2 #4 this works. Any ideas as to whats going on. Is the book wrong or has somthing been chaned to make this happen. Thanks for any help. Signed FRUSTRATED.