Part Specs & Drawings

[74CREWCAB]

Is there a place where GMC/Chevrolet stores (archive library) part specs & drawings for these old trucks? The parts that I need are either obsolete or discontinued. How do I find info on parts and part venders/manufacturers utilizing the GM OEM Part Number?

The part most needed -
Chevrolet Part Group 3.164 (GMC Group 7.8215)
OEM Part Number 338613
Cable Asm, fuel tank selector
1973-74 C-2,3 (Cab, 4-dr) w/aux tank (454)

None of the aftermarket parts venders carry it because of the very low demand.

Hoping there is a member that works (or knows someone) for GM archives / historian that can assist me.  

[77c15]

If you can't find what you need from   Truck, try www.gmpartsdirect.com and put those part numbers in. You'd be suprised at what those guys have lying around! Hope this helps!
-Mike