A spacer would have been on the truck from the factory but it is not needed. Some engines used a governor so the intake studs were too long without it. The spacer allowed common intake stud lengths.
You'll probably need to use heat to free up the riser. The butterfly is brazed and would need removed to install a new shaft. Don't know if anyone makes a replacement but you don't need one since you'll already have to remove the butterfly. Ream the intake and install brass bushings before reinstalling the shaft so a rusted shaft will not seize it in the future.
