So upon loading into the garage for the first time on flooded foothills, I had obtained both the 770G as well as the TH357. After leaving the garage both can be obtained by completing missions. Well at least one can at the moment. The TH357 mission currently cannot be completed.
Starting a new game gives you both vehicles upon reaching the garage in Michigan. As to why this is a problem, selling both nets you over $300,000. The in game economy is questionable at times but this is broken. At least starting with the Khan Marshall in the garage from the start you couldn't instantly buy nearly any truck with the $20,900 value. Considering that neither of the new cat vehicles would help a new player in any other map, selling them is the obvious choice.