Maybe Tesla could learn a few tricks from old General Motors (NYSE: GM): The manufacturing "ramp" for GM's all-new full-sized pickups appears to be a bit ahead of schedule.Earlier this year, GM said that its all-new pickups would begin arriving at dealers this fall. But the first new trucks have already arrived, and while it's very early, dealers say they're selling quickly -- two very good signs for GM's bottom line.Some of the first new 2019 GM pickups to ship were high-profit GMC Sierra Denalis.