I just purchased what appears to be a Stickley open-armed rocker with back cushion (5 slats on back). It is not signed, but has the number 316 641 burned in on the bottom of the back section of the chair just above the seat. How can I confirm that it is a Stickley and how old it might actually be?

This is a great looking chair, from the side anyways , Is the number truly burned in or is it a black stencil? I'm going to venture a guess it might be a Stickley Brothers chair. The early Stickley Brothers catalogs have a model 641 that has the same double through tenons and no corbel style but not the extreme lean. The later 1912 catalog has a model 741 that has the exact look except for added stubby corbels. Unfortunately all these pictures have back cushions that block the slats so we don't know how many. However, a price guide by Warman's has a chair that looks pretty much exactly the same and has the 5 back slats, but it labels it as S Bros model 604 but with a question mark, and dates it 1912-15. This model number isn't in either of the 1912 or 14 books. Putting the pieces together, it might be the 641 model, with a style change, from the gap in the catalogs between 1908 and 1912, with a model number change by 1912 or conversely a dropped model 641 by this point. Can you confirm some dimensions? Hieght, width, depth? Value, assuming it is Stickley Brothers, finish looks original and a little worn, assuming no repairs or big faults, cushions replaced, I would say similar to the Warman's book at $1800-2200.

I think your right stonecat...stickley bros for sure. I've seen morris chairs with the lean in the lower seat boards instead of just in the arms. Which in a rocker you wouldn't hardly notice because of the natural lean back.
And as you know it's so hard to go strictly from the books because of all the un-catalouged variations they made. It's very easy to have different corbels, or the lack of thru tenon's or pegged versus not pegged. But I concur, I think you right on with this one.

I like the lean, sort of like sitting back on a chopper with big wide bars, not that I've actually done that. There was a leaner Limbert on eBay a while ago but alas it blew past my bids.