Yep .... dang confusing.
The "style" actually refers to "when" it was made, which affects the hinge type (most vent lids in the last 8 years seem to be the newer type that require manipulating the hinge ends with a pair of needle-nosed pliars.
The installation instructions would be a lot more helpful if they said "hey dummy, go inside your trailer for this part" when you get to the screw removal & then "hey dummy, go back outside" for the rest of this.
Another helpful hint on the instructions would be ...
"Yes, we know it almost looks like you could do this much easier another way.... but don't bother, we spent a lot of money to engineer this thing so that you will fail by 1/8" of clearance, after an hour of effort, if you try
Biggest hint I can offer ...... if your removing caulk, your doing it wrong.