i also recently (like, last week) ordered a Robert Shaw from FlowKooler and received the correct part.
Here it is next to the Motorrad that I got from Mopar.
I put them both on the stove in a saucepan full of water and found that they both open on the dot at 195, are stroked open 6mm at 210, and close off on the way back down at about 187. Robert shaw doesn't have a jiggle pin, but the one in the Mopar/Motorrad doesn't work in a horizontal application anyway. If you like to drill a hole to expedite air bleeding on refill, I'm not sure where you'd put it on the Shaw.
The Shaw looks completely different than any other thermostat I've ever seen which makes me curious about why. The larger plunger diameter of the Shaw adds about 50% to the flow cross section, and if it does flow significantly more, all it would do is shrink the difference between the water entering the block and leaving the head...but if AMC or Jeep/Truck engineering thought whatever difference they designed for was fine, then what is there to gain by changing it? Another thought is that the flow may end up as a wash since the plunger is all the way out so close to the hole in the cylinder head that it lives in. The best I can come up with is that being up against the perimeter could possibly result in a more linear flow vs stroke relationship which could smooth out the slight oscillation when the thermostat initially opens. What I can't figure out is why that would be a problem that needs to be solved. Maybe it's as simple as Shaw developed or re-applied an automotive thermostat, without looking at another automotive thermostat, so it just came out looking different.
The exercise gives some perspective on why we see so many blatant copies of American-design products come from China, or companies offering useless components like a drop pitman arm in a coil spring lift kit that doesn't change the track bar. Figuring out why someone else made a particular design decision can be almost as tedious as just engineering your own from scratch. It's much less work to just copy it without questioning anything.
At any rate, I'm not advocating for either one. They're close to the same price, Shaw probably has a better reputation (judging by the gnashing of teeth we have about our favorite thermostats being replaced by Motorrad) so I'm going to install the Shaw and toss the Mopar into the parts bin.
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