Received the above part via USPS the other day. Just now installed it. A nicer piece than the one from aftermarket supplier GENO'S GARAGE (whom I otherwise highly recommend). Left three of four flaps open for our "winter season" of around ten days (temps stay below 60F in all instances). The next six days is just going back & forth to work. The grille block was removed during the towing trip south (above) and not reinstalled.
Temps going to work (7-miles) get up to 160F pretty easily with ambient of around 60F. Op-temp is 188.6F. We'll see how this piece works as temps are now low 40F, high 50F daily for this week. When I keep the block heater plugged in for around 2-3 hours, the engine coolant will come up about 50-60F from ambient. So, I expect to hit the op-temp mark on the way to work (any hour of 24) and look forward to how it does on the return.
All of this is something of "just an experiment". I expect to move north in the next year or so, so am having fun establishing a baseline for use where the temps are marginal for such.
The sides attach with included velcro strips. The top is a combination of clips and velcro. The lower side is clips. The heat exchangers are all of them open to airflow at bottom.
One post by a man from Canada indicated that it was his opinion that the open bottom allowed for "cooling" to some degree. My experience with big trucks is about the same. Keep the fan area open in all but the coldest temps and that -- plus open bottom -- will keep things okay.
My end of it will be the next time I am off and going out on my errands round. If temps permit, we'll see how far under what temps this device is workable waaaay down south.