'78 GMC Suburban V8 Fulltime 4WD Ambulance

[gotfivebucks]

Hi all you chevy folks!

I just became the owner of an old suburban. I am new to this, but want to replace a lot of parts (engine parts, alternator, brake calipers,tie rods... etc. etc.) I am looking for the best online resources and groups for folks talking about parts, repair and maintenance for this old thing. It is a 1978 15 (sometimes listed as "C-15") series Fulltime 4WD 1/2 ton Suburban (V8). I don't know if that means it is a GMC Sierra 1500, or what, but I would like to know. Motor is a 400-4 (~6.5 L). I am most immediately trying to figure out the exact specs for it -- the body has been stamped with "GMC series 15 Sierra", but the VIN indicates that it is a Chevy Suburban. I am also wondering where parts for these things are being manufactured nowadays. Would all parts be aftermarket if not from a junkyard? I have many other questions. This rig used to be an ambulance (has a modified hi-top)and it has two alternators, two batteries, a kill switch, a serious inverter/charger, and some other strange modifications, some are hooked up, some are not. I think only about 500 of these were made originally, but I have no idea how to go about getting a wiring schematic for it!! I also need the best and most comprehensive repair/maintenence shop manual available for this vehicle (for overhauling, teardown and rebuild) and I've only heard Chiltons... is there anything different or better or more specific to this kind of vehicle? Is this the right place to look for help? Any suggestions would be helpful. Thanks!