78 gmc factory assembly manual?

[78 GMC Truck]

Does anyone know where I can get a FACTORY ASSEMBLY MANUAL for a
1978 GMC, Sierra 15 (Straight 6 motor) Pickup Truck?

I know we are mostly talking about trucks here, but, I would also like a FACTORY ASSEMBLY MANUAL for a 1998 Dodge Ram Van, 3500 Series?

Just to save time, I am talking about the FACTORY ASSEMBLY MANUAL
(Not to be confused with the Service Manuals)
that GM provided to plant workers to put the car/truck together from A-Z.

Thank you for any help,