Greta Grossman grasshopper lamp  

Pegboard, I've never seen a...
Pegboard, I've never seen a Grasshopper with the kind of joint used for the black lamp in your post. I have a feeling it has been altered at some point in it's life, since even the earliest versions seen in Grossman's own home and in the first Ralph O Smith Ads looks just like the one Noah posted in the "The last thing you acquired" thread.
The yellow lamp looks like the second Ralph O Smith version, which is the most common version to see for sale in the US. One thing which I first didn't notice and which I have also never seen, is the brass cap on top of the Swivel joint. Do you think it might have been replaced at some point when the lamp was rewired?

Fastfwd, the green lamp you...
Fastfwd, the green lamp you posted in the "The last thing you acquired" thread, either had the joint replaced at some point, or it's quite possibly a copy.
Prescolite made several copies of Grossman's lamps (for example the one wrongly attributed to Grossman in Taschen's 1000 Lights, Vol 1, pg 431) and they used joints just like the one in the pic you posted. These lamps were was part of their "Stylite series"

For sanity's sake
I'm going to move some of the posts from the "acquisition" thread to here so we are not constantly referring back and forth.

fastfwd's
Easiest way to tell that it's a replica is to look at the way the shade is mounted. On the original lamps, the frame tube terminates in a "T" into which the shade's ball-joint is fitted.
Photos, top to bottom:
One of the original lamps that sold at Wright a few months ago for $13K.
A closeup of the faithful reproduction that Gubi's been selling for about a year.
Your lamp.

noah's
I was pretty sure it was real and very early. I got it from a sweet old lady who was the original owner. She had all those Tuttle stools and a set of 4 Eames wire chair rockers. She wasn't ready to let go of those! But she was definitely a collector from the era. It seems that the T joint was a later addition to the Grossman lamp. The hardware on mine is just like what was on the one that was in Greta Grossman's home for a promotional photo shoot in 1948. I would be surprised if she had a knock-off in her own home! Some of these earlier examples of the lamp have sold at Wright and been featured in reputable shows.
see the table lamps here:
http://www.lamodern.com/featured-artists/greta-magnusson-grossman/
and the Grasshopper lamps here:
http://designapplause.com/2012/modern-design-auction-wright-auction/24033/

Mine
You and alexandersforum are correct. There are different generations and different manufacturers of the grasshopper lamp and I believe yours is authentic.
Here is a detail of the pair you linked to. The neck/ head transition is the same as yours.
There are a number of details that vary among the different generations and makers of the grasshopper lamp. I have seen many of these in person, inspected them closely, compared and contrasted them and I've yet to sort it all out. I would be interested in seeing more detailed shots of your lamp. Besides the neck/ head juncture, I'd be curious to see the head (number and placement of holes) the feet (with a measurement of the diameter) and overall measurements.
The one thing I do know is that the knock-offs or copies have very significant differences in the design and construction and after looking at many of these I can tell you that they are pretty easy to spot.

fastfwd again
I'm certain that Pegboard has seen more of these lamps than I have, so I'll defer to his more-expert opinion. Noah, I apologize for making that snap judgment; I hope I didn't cause you any distress.
I've seen a number of Grasshoppers, and the only non-"T" authentic lamps I've ever seen have a swivel that looks like the one in the photo below, which was also used in at least one of Grossman's other lamp designs.
I've never seen a real Grasshopper with a swivel that looks like Noah's, but I'd love to learn more. Pegboard (or anyone else), do you have photos of another authenticated example with a swivel like the one on Noah's lamp?

And noah again
The lamp's feet are roughly 1 inch and 5 8ths in diameter. The lamp is a little over 4 feet and 1 inch tall. The shade is about 9 inches long. fastfwd, the joint looks like the ones that pegboard posted above. The one you just posted looks like the real lamp but possibly with an altered joint.
here is another authenticated one with the joint that matches the lamp I have:
http://www.liveauctioneers.com/item/8755807
I'll post a pic of that with more pics of mine below.
Thanks

Now we can continue
... the discussion being able to see what has been written and shown.

Thoughts?
Is this the same one you showed the detail of fastfwd?
http://www.sothebys.com/en/auctions/ecatalogue/2012/20th-century-design-...

Yeah.
Yes, the detail I showed earlier was from that green lamp that sold for $4500 at Sotheby's in March.

There's also
a version from Sweden that has a big hinge at the tip of the frame tube. The shade can pivot 180 degrees, all the way up until the lamp is illuminating the ceiling, but it only moves in that plane; it doesn't tilt left and right like the later ball-joint lamps.
I've only seen pictures of that one; if no one else posts a photo of it before I get home tonight, I'll post one then.

Here's that hinged version.
Sold for $4900 at Wright in May. From the catalog:
early Grasshopper floor lamp
Bergboms
Sweden/USA, 1947
enameled steel and aluminum, brass
14.5 w x 16 d x 48.751 h inches
The early Grasshopper lamps were made in Sweden and feature different details including a hinged shade allowing light to be projected upward. Signed with decal distributor's label to shade: [S].
Literature: Greta Magnusson Grossman: Designer, Kane, pg. 6