Today on my return trip with a new sediment filter for my 59 Cockshutt 550, I hit several large puddles on a back country black top. Suddenly I noted a stiffness in steering, and the check gauges light was on. I thought I stalled, so I braked gently and placed tranny into neutral and tried to restart. The starter protested letting me know that the engine was still running. I stopped my van, and began to inspect under the hood, and quickly noticed my serpentine belt had come off! After about 45 minutes of first figuring out the path of the belt, and then realizing I don't have the right socket or crescent for the job (stupid brake line elbow is right in the way of running a normal socket setup with a 15 mm) I pulled up on the belt just aft of the alternator and was actually able to pull the tension pulley just enough to get the belt onto the alternator pulley. That was without loosing a finger tip. But now I can't get it to run and I am pulling codes 12, 43, 25, 41, & 55 in that order. The battery was low, and a kind passerby attempted a boost, that may explain the code 12. I realize 55 is end of codes stored. It appears that I either have an electrical problem, or a vacuum leak. There was a squeal for a bit this morning when I started out, which likely explains why I was able to man-handle the belt back on (weak spring on tension pulley), and of course why maybe a jet of water directed by the right front splash guard was able to force the belt of in the first place. The starter motor turns nicely on a charged battery, but still nothing. I pulled some of the plugs and cleaned them up while I was waiting for a boost.