GMC history

[factorystock]

GMC pickups pre '70 were always known as being different than Chevy pickups. Many claim they were a bit better, had heavier duty engines and suspensions than Chevy, and some say they were the upper end of pickups, like the Cadillac over the Chevy. After around '70, essentially, they were the same pickup, just a different nameplate. Why even have a GMC nameplate if both pickup lines became one after '70? Why even have both GMC and Chevy large truck nameplates if they also became one? So, IMO, after '70 why not all pickups be Chevys and all large trucks be GMC's? Why did GM put up with all the infighting between brands and dealerships trying to undercut the other guy and concentrate on one thing and one thing only?