Sometimes finding parts is easy. There are many websites to help you pick manifolds and camshafts.

Sometimes you need to find the right part number for the GM part, so you can then cross reference it to something that is now supported by the aftermarket suppliers. Sometimes the GM number is good enough, and you can find the part number on ebay. There are guys that liquidate auto parts from stores and dealerships and they often do not know what the parts are. They just know the numbers on the box.

So if you are looking for a part, sometimes a keyword search can be done with Google, targeted on one specific website I enjoy, "GM Parts Wiki".

It is an index to a bunch of GM parts manuals for a broad range of marques and models going back to even before I was born. The search tool won't bring you to the exact line, but it will get you to the page.

Sometimes you can get diagrams like this one.

http://www.gmpartswiki.com/getpage?pageid=39082

But that is kind of rare. More often you get parts lists like this one:

http://www.gmpartswiki.com/getpage?pageid=38320

If you have the P30 chassis in your Barth, the engine is often the W version of the 454, and that engine is also used in the 1 ton pickup trucks of the era. You won't specifically always find what you want in the P30 manuals that are scanned, because not all of them are. But there is enough overlap with the pickup trucks and the school buses that often parts can be identified, with a bit of guessing too.

This has helped me to find the gasket for inside the oil filter mount housing with the oil lines, rubber inserts for the holes in the rocker covers, air injection tubes, diverter valves, and helped me get a "saved search" going o ebay for the PS/PB pump pulley.

Happy Wrenching!
Matt

Thanks for the wiki. I'm already looking up parts for my Barth.
Anybody got an original air cleaner and pipes they want to part with?