I found a 81 Winnebago Warrior on the internet that had the VIN number included (1981 Winnebago Warrior Class B Motorhome - RV in Stevensville, Michigan
). The VIN number for that one comes back as a P series chassis. While a Class A P30 version is a 1 ton chassis, the Warrior came back as a P20 3/4 ton chassis. If that is all true and yours is basically the same as the one at that website then the chassis manual for the Warrior would be the same as the Class A P30 series chassis. That manual is the Chevrolet Light Duty Truck series manual for 1981.
EBAY: 1981 CHEVY GMC 10-35 PICKUP TRUCK Shop Manual CD | eBay
Bishko: Bishko Automobile Liturature available for 1981, Chevytruck, Shop Manual
CD-ROM version contains both the service and Unit repair information. You would have to purchase both paper books to get the equivilant.
As ar as the coach itself. Your only hope is Winnebago