Can you tell the type of boxes apart based on what frequency they'll put out? Well, yes and no.
Yes in the fact that different boxes reflect different eras Whelen produced said box. The #1 box above is an earlier box...totally rectangular. I'm guessing the first picture is at a 2700 and there's an -864 in there.
The second one you post has the battery box inset with one door. This is the kind of cabinet Whelen is currently using on its sirens, and the electronics cabinet is elongated regardless of how many amps are in there (it used to vary based on if it had 1-5 amps or 6-10 amps). Given the logo has bleached off, I'm guessing this one has been up for a few years and is at the end of the 440 hz period/beginning of 560 hz period.
The third one is the squished box with inset battery cabinet introduced around 2001. I'm guessing that's a 2800 installed 2007 at 440 hz. BTW: If you've got 28xxs installed around 2007, those were easily some of the last to come off the production line as the first 2900s went up summer of 2007. The VERY first 2900s sounded at 440hz, but those are few and far between.
The current Whelen cabinet can be easily seen in their catalog:
http://www.whelen.com/pb/Mass%20Notific ... cation.pdf
But anyway, that's the yes. The no is in that's by no means an indicator of what you'll see since the frequency is aligned with the controller and the cabinet is not really aligned with the controller. Especially with that second pic, its difficult sometimes to tell if those are 440 or 560s with 6-10 amps (though the 1-5 amp 440s will look like the third picture almost always). Also, the -864s came were frequency adjustable. Whelens lowered the frequency of the analog controllers several times in its lifespan (from 800+ hz down to 460 hz), then had the digital -864 (what we equate to the 465 hz controller). Those controllers are easy to tell because they were really brought around for the 2806-2810s (so you have a box that is elongated with two separate battery cabinets to accommodate the 6-10 amps). But the 1-5 amp box on the digital -864...you really can tell them because the battery boxes aren't inset but the metal on the boxes appears more...refined...not like the first picture where the doors are so offset from the cabinets (hard to put it any better than that).
And of course, none of this takes front panel upgrades into account...
I hope this makes sense and isn't one big ramble.