Harbor Freight will become a good friend. Had to upgrade almost all of my air tools when I got my deuce to 3/4" impact. At HF, they are relatively dirt cheap - and always bring the 20% of coupon (ideally wait until it's on sale/clearance, then use the coupon). Was told the 3/4" impact wrench I purchased from them (Earthquake branded) was a re-branded Ingersol Rand unit, but it's good for 1400ft/lbs and has always worked great.
The biggest adjustment I had to make wasn't necessarily having the correct tools, it was the shear level of force required for some jobs that I had trouble mustering (e.g. Torque bar replacement). Being only 165lbs, that didn't help at all, but hey if I can do it, anyone can. Hope you win your M817 - just PM it really well and welcome to the club!
-Frank
PS - side note - there is an outfit on eBay that resells returned HF tools. The 3/4 impact gun I mentioned above I got this was for ~$100 (vs. $250) and it was only lightly scuffed..it's a lot more scuffed now =)
EDIT - almost forgot - if you don't have them, please get/borrow a few sets of heavy jack stands as normal ones typically aren't rated for your truck. I bought a few 6 ton sets (from HF of course), but I think they have the 12ton sets now, which I would have bought if they had them.