Can anyone tell me if this is a fake Z61 tailcap?

So I thought I found an original Z61, but when it arrived today, it appears to me to be a fake.
The clicky function is VERY hard to activate. Light press works ok, but the spring or switch is way too stiff. None of my other E series are like this.
Also, the knurling looks a bit off, and the underside, where it contacts the body, looks strange too, not like the others I have.

Cant get pictures to load, which makes it a bit more difficult....
I think I got it now.
First is the one I received, second is from my E2LAA, same from that view as my E1B, and my E2DL Ultra.
Third is side by side.

I asked the seller about it, and he stated there was a recent thread, here he thought, about the differences between the variations of Z61 tailcaps, and that this was an early version, of the hard press variety.
Anyone know where that thread is? I searched but couldnt find anything like it.

Well, call me surprised that no one has responded....I thought for sure if anyone knew, they would be on this forum.

You may be thinking of this thread ...

https://www.candlepowerforums.com/threads/375954

... the utility of which is now rather compromised by the loss of relevant photos

Have you contacted SF directly about this ?

On their website, they request information about potential counterfeit concerns.

CPF member @Rat is probably the best expert on these, but I haven't seen him around for quite some time.

Other prominent collectors may be equally knowledgeable, but they might prefer not to address these matters in open postings.

Some of the photos from @Rat were saved here, in this article on FlashlightGuide ...

http://flashlightguide.com/2013/12/beware-counterfeit-surefire-parts/

After looking, I cant say for sure its a fake, but personally believe it is. The link to report to Surefire isnt working for me. It brings up the counterfeit page, but wont go anywhere else. Ill try again later from a different computer.
Ive seen some Surefires with stiffer click switches, and the feel of them is different. This one feels cheap, not like a standard Surefire.
Again, Im not 100% sure it is a fake, and even if it is, he might not think it is, so Im going to give him the benefit of the doubt, and not going to out the guy here, as he has several Surefire sales on eBay, and 100% feedback rating so far.
Hes paying shipping back to him, so I guess Im not out anything, but considering I can get a Lumens Factory E series tailcap for about $25, Im going to go that route instead as I wont have to wonder about it, or disassembly one of my other E series to get the correct click switch in it.

Please keep us updated, if you find further info on this issue.

I just received one yesterday and having the exact concerns as op. It is very hard to click on and it rattles when on the on position. Got it off a ebay from a reputable seller as well but im not educated enough on the different types to say it's fake. It definitely isnt anything like my other e series caps and i have about 15 of them. Anyone have any input?

The middle one is the cap i just got, left is off a e1b mv and right is off a e1l outdoorsman

It's hard to tell from the pics but both suspects look like they have McClicky installed in them.

However, 'hard to press' is a surprise if it is McClicky unless hard rubber cap was used.

As far as rattles concerned, not sure.

scratch that. Just looked at my McClicky and it doesn't look like the mine in the pics. Sorry.

It's not a hard press boot it's the switch itself that is very hard to press. At first i thought it was a momentary only