I'm not sure if the shocks match exactly, but the 2013 RT's (with the V-twin motor) & 2013+ RS's, RSS's, & ST's (also with the V-twin motor) are very much the same in most other ways, basically except for the tupperware; while the F3's of the time were a whole new animal; IIRC, even with a different belt length & therefore swingarm/mount differences, so quite likely running a different shock/coil length/spec... I'll gladly stand corrected if anyone knows for sure about that, but personally, I'd be more inclined to take a punt on the RT shock than the F3 shock.
That said, if you're prepared to pay for going new and want something better than OEM, but don't want to sell your arm, leg, or kidney just to fund a shock, you might try IKON Suspension (bloody auto correct is back on somehow, I keep turning it off, but here it is today, correcting IKON to IKNO for me!!

) IKON is an Oz shock maker, and beyond what's shown in their catalogue, here in Oz they are very good at taking all the details you can give them and building a very good shock for a very reasonable price. They might do the same for you in the US, and they do have a presence over there, check out:
The Best Aftermarket Motorcycle Shock Manufacturer In The World
ikonsuspensionusa.com
So if you can get your shock off and provide them with all the necessary details, your weight, load weight, riding style, needs, and wants, etc. they juuust might be able to build you a pretty good shock for somewhat less than Elka wants for a shock that you'll still probably need to pay to get rebuilt every couple of years or so! I'm
still running IKONs all round on my 2013 RT, shocks that I purchased & fitted after the OEM stuff failed (again!) early in the piece, and they're still going strong even after all this time/waaayy more miles than many do in a lifetime of riding, let alone on the one Spyder! And as I mentioned above, I got all 3 shocks for a very reasonable price, less than it would've cost me for just 1 of the brand name jobbies!
Just Sayin'
