I've recently purchased an old FedEx truck and I'm converting it into an RV. I'm having problems finding information on the next in reference to the chassis model P42... Any help?

Also, has anyone changed the rear axle to a 1 ton in order to decrease the gear ratio? 5.65:1 is a little too high for my liking... Any help?

There are some P42 manuals from GM on ebay now, for the years 1996-1999.
Matt