You can download the manuals from the .mil pubs website. I have all of them on a thumb drive if you cannot find them, send me a PM with an email address and I will send them to you.
I'd swear there is a local guy in Tampa with surplus tires, but if you have a spare you are in business.
I bought mine down the road at Ft. Gillem. It was running with two brand new steer tires and 6K miles. I had the Cat guys service the truck and drove it home to Washington state the following week.
If you get the truck, you might need batts, but they prolly work. If you ask the GL guy nicely, they might go start it for you and have it charged up. Mine said," starts and runs" and I asked that it be started and running when I picked it up. Since that was the condition I purchased it in.
Don't plan on driving fast, an A3 is comfortable at between 48-50mph. Anything faster is bouncy or high revving. A Cat dealer will have the fuel and oil filters in stock if you need them, I changed mine but they looked fine. The alternator belt could be dry rotted and it is a pain in the a$$ to find. Check with Eriks Military Surplus if you think you need one. Bring a lock for the steering wheel chain to secure your deuce.
The worst thing most guys find is the insulation in the roof is rotten and that dry dusty crap falling out of it will kill your eyes, either remove it or smack it til the dust stops falling out or you might go blind to drive it home. Mine killed me for two days before I got it handled.
Congrats, I love my A3, it runs like a champ.