Early Eames RAR Base?  

No
That rocker base would not have been attached to a Zenith rope edge armshell. Maybe a transitional Zenith shell. The runners on the early rocer bases are more slender and have softer more rounded edges.

Thanks. Good to...
Thanks. Good to know!
Would anyone here be able to post a close-up photo of an early runner for comparison?

I'll post one...
Not at home at the moment though.

I was digging around on the W...
I was digging around on the Wright Auction site and found at least one chair with similar rockers. You're right though, the vast majority have very rounded edges...
http://www.wright20.com/auctions/view_search/HYN4/HYN5/259/LA/eames_rar/...

In addition to questioning...
In addition to questioning the rockers on this chair, I'm also confused by the shockmounts. As you can see on the photo, the two front mounts have notches out of the rubber beside the circular washer recess. I can't find another like that. Could this mean that the shell was attached to something other than a rocker base?
Thanks again!

I'll check mine when I get home.
I think these are close,but not quite

H base
Those indentions are from an H base. And by the looks of it, the shell was mounted on it for a while without washers. A definite mix and match sadly. Why it was mounted on the H base is anyone's guess.

runners
That base would have never been on a transitional shell either. It's my experience that Herman Miller started using the squared off runners in the late fifties or early sixties through the end of production.

josh
I'm afraid that it's pretty clear that the rocker base is not original to that rope edge armshell. It's a "marriage" of the two.
And jeffery, I'm afraid I have to disagree. I've had transitional Zenith RARs of impeccible provenance (purchased from the original owner, with almost zero possibility of having been tampered with) with the more squared off runners. I've also had transitional armshells with the same runners as rope edge, so my thought is that the change was implemented late in the run of Zenith shells. It may have even happened once Herman Miller assumed production of the shells and they were finishing off the last of the stock of Zenith produced shells.
Same with Zenith chairs with X bases. While the rope edge chairs mostly had domes of silence feet and the transitional shells had slip-on boot glides, there appears to be a period when they made the change that some rope-edge chairs were fitted with boot glide bases and vice-versa.
Here are two examples of transitional Zenith RARs I've had. The one with the painted shell and green slip-on cover I'm positive is all original, and the parchment one I had no reason to question.

Thanks again for all the...
Thanks again for all the input. My wife and I have been looking for an early rocker for some time. Never seen one in the flesh though - our city seems to be vacant of any vintage Eames pieces. Thus, I'm stuck with Ebay and all the fakes. There's a nice looking yellow one on there now, but again, how could you ever be sure it?s ALL legit?

Josh, I feel your pain...
I had my eye out for an early rocker for quite some time myself. I finally found mine at a local auction house that has a "Modernism" auction twice each year. It turned out to be, from what I understand" to be the earliest of production models, the one with the funky base. The struts aren't all quite arrow straight, but I felt like I got a good deal. Not sure if I'm reading this thread correctly, but if you're looking to buy one, I've bought items from Pegboard who has been replying in this thread and am DYING to give him more of my money. He always has great stuff and I'm sure he probably has one or could find you one if he doesn't. PLUS he's a standup guy to boot...and is quite handsome...and has a lovely crazy haired child who may need counseling at some point to help cope with all that curly hair. Our daughters is worse, she is going to be a wreck.