Chevy vin decoder
http://chevroletforum.com/forum/vindecoder.php,
The vin is normally on the top of the dash at the left hand side, usually a metal plate rivotted in a cut out on the dash.
For parts I always used Rock autos in the states. When ordering make sure the goods all come from the same warehouse as it affects the shipping charges. It may be a case of ordering a set of spark plugs that are 2 dollars dearer to keep the goods coming from the same warehouse. Take care when selecting the delivery option. I always choose Fedex priority and taxes and fees were paid prior to dispatch and the goods arrived within 3-4 days in N.Ireland. If you choose usps option the goods can take up to 45 days and wont be released to you when they arrive at customs til the tax and handling charges have been paid.
Cost wise the parts are very cheap in the states, unfortunately the postage can be twice as expensive as the parts. However they are seldom as dear as european vehicle parts when the postage is added.
http://www.rockauto.com/en/catalog/
Filters are often available in the uk for example the chevy 350 5.7 lire v8 uses a fram PH30 filter, belts and serpantines are standard and can be purchased from motor factors.
Brake pads etc are available on Rockautos site. The trick with these is to look for a union jack on the delivery truck symbol beside the description. This means that they are available from the UK manufacture direct eg EBC brakes and therefore much cheaper to ship. Strangely these deliveries take longer, perhaps a week.
Best of luck with the rv
Paul