Signs that suggest these ARE JBL kits installed: the purplish-brown color approaching the surround cloth overlap on the back, the surround accordion shape, the ribs on the front, the gloss black glue holding the VC leads on the cone, and the VC lead placement angle.
Three things I see that look wrong: the point where the VC leads go out the back of the cone looks a little too far away from the first rib, I can't see any sign of the glass reinforcing fibers intermingled in the cone paper, and the completely lack of signs that the cone is ribbed when viewed from the back. I didn't see a cone number stamped on the backside of the cone.
It is possible (but unlikely IMHO) that these are early 15" 2226's: I have 4 early 12" 2206's that have the leads going out the back of the cone more near to the center of the cone, about the same distance from the first rib, as your picture shows. The new JBL kits I got for these have the leads a little further out. I think JBL corrected a tinsel lead issue by moving the leadout point further out on the cone at some point in production. I can't find this on any of my 2226's, so I can't be absloutely sure that they did this on early 2226's as well.
Another thing not shown was the dust cap itself and the glue joint between it and the cone. A factory JBL dust dome has no flanged lip where it meets the cone- the cap is literally a dome with its' cut edge contacting the cone glue joint. The factory-installed kits have the most perfectly smooth bead of black glossy glue applied to the joint that you will ever see- Even most Factory-Certified techs at Factory-Authorized JBL Service Centers cannot approach this level of smoothnes in their glue joint, simply because they don't have the assembly-line tools and experience to do so.
Regarding the labels: Factory-installed kits from when the driver was originally built new will usually have a white label on the frame, not the cone itself. It is ~1/4" high x 1" long, rounded on the ends, with the code xxx-JBx, where the first three characters are the date code, the JB means the factory assembly line in Northridge, CA (now closed and moved to Tijuana, Mexico), and the last character was which production line it was built on. Sometimes there is a "2" after it, indicating (I believe) that it was built on the 2nd shift of that day.
Replacement kits have the same code label on the box, and a similar label on the back of the cone itself, which reads xxxxx- xxxxxx. This number is the JBL recone kit serial number, also found on the large label wrapped around the corner of the box it was shipped in.
Sometimes this label will fall off of the cone of the recone kits, but most of the time they are on it. You can usually find it laying in the cabinet that the reconed woofer had been installed in.
The cone number stamped in white ink on the backside of every JBL 2226 kit I recall seeing is: 71649-02.
Every JBL VGC kit I've ever seen -12", 15" or 18"- has a slight rippling on the backside of the cone as a shadow of the molded concentric ribs that are prominent on the front of the cone.
Hold your woofers up in bright light -better yet, take them out in the sun- and look for the glint of very fine glass fibers. It looks like 'angel hair' or fine spider web threads.
If your cones don't exhibit all of the signs I mentioned, then it is not a factory JBL kit.
There is one aftermarket kit supplier that uses the same OEM cone/surround part that JBL uses, but that is where the similarity ends. The coil, spider, and dustcap are all different. And, you have to hand-assemble these individual components, placing a great deal of precision in the hands of the repair tech.
The JBL factory kits are preassembled on a jig, which gets the coil and the spider height and angular alignment perfect for a guaranteed recone performance specification if the frame and magnet are healthy and straight.
In other words, you get what you pay for. There's a reason that the factory kits cost $176 and you can only get them as an installed part from a JBL Factory-Authorized Service Center.
Regarding the "sunken cone" issue- you're right- they've had it. the spider and surround are stretched out... the coil only has .3" overhang in the magnetic gap, and this 'sunken cone' places the coil offset into the magnet, creating a non-linear drive motion as the cone excusion goes in and out. Recone is the only way to fix that.
I hope you got them cheap! $50 is the most I pay for rebuildable cores.
BTW- the 12", 15", and 18" VGC woofers use the same coil and magnet. The only difference is the cone and frame size, and perhaps the spider stiffness varies with cone size.
Hopefully, this answers all your questions and removes all doubts.