The following slight variations for the Marine Corps seem to stem from the difference in guard chain of command:

6. To receive, obey, and pass on to the sentry who relieves me all orders from the Commanding Officer, Officer of the Day, and Officers and Noncomissioned Officers of the Guard only.

9. To call the Corporal of the Guard in any case not covered by instructions.

In addition, I learned these unofficial General Orders from other bored Marines on post:

12. To walk my post from flank to flank and to take no shit from any rank.

13. To walk my post, 'round and 'round, fuck this shit, I'm sitting down.