The cans I have don't have the old threaded caps, but a compression style cap (and nozzle).
I had to buy an extra one or two of the nozzles to end up with several that didn't leak, but I like what I have now.
I think the swing gate will work with a liftgate rear end as well as the typical tailgate of a truck... either way the swing gate attachment has to move completely out of the way for the back of the vehicle to be accessed properly.
Also, since plastic breathes (in a manner of speaking), I don't think the shelf-life would be as long as with something that offers more of an actual air tight seal... and never really cared for the bright red color of the plastic... give me OD green any day.