This should be a redundant question - not least that the Tech Manuals posted on this forum at the top, explain suspended towing in the M816 Operations Manual under Normal Conditions, BUT if you are paying for a tow truck then HE should know or be able to ascertain any and all requirements for moving a large vehicle regardless of condition - imagine what a trained operator has to do at a crash site when the truck driver is on his way to the hospital or worse and the LEOs want the wreck moved pronto.
Then there is the liability of you telling a towtruck driver how to do his job. By all means explain the different knobs and levers if he ask you..... One side note; if he is younger, then he may not know about air over hyd brakes and that the military glad hand valves work backwards - 90deg to line is open. Then again, he ought to be able to figure even that out too.
I don't mean to dump on you but I think you will be ok with letting the towtruck driver figure it out - assuming he is a pro. Different matter if you were asking a buddy with another 816 who got it for fun - as may happen down the road when you have yours all up to speed. You'd be amazed how owning a wrecker gets noticed locally and people want favours.....
Looking forward to more wrecker pics and hearing how you make out - how much restoration do you intend to do - or is it a finished project?
... and again I say did not mean to be insulting or anything.....
