If I remember correctly, it was a Testor's-branded kit, so if you're interested, you can Google it. I had this kit in 1980.
I don't think I have ever seen one like the last one, so it is a modified COE with the drivers compartment raised to allow the lower cars nose to be were the driver usually sits. Interesting.
The driver of the prototype of your triple-decker must've had to take every exit, because there's no way on God's Green Earth a real triple-decker with cars loaded stayed under 14 feet overall height. But that's a nice diecast. Is it a Dinkytoys brand?