I think I've partially answered my own question. I found the following on another discussion website:
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Stuller Solstice Styles
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SH156 Bombe' Shank for a 4 Prong Setting
20601 4 Prong Round Setting Medium Height
20603 4 Prong Round Setting Tall Height
SH172 Bombe' Shank for a 4 Prong Cup Setting
20608 4 Prong Cup Setting Medium Height
20616 4 Prong Cup Setting Low Height
SH160 Bombe' Shank for a 6 Prong Setting
20605 6 Prong Round Setting Medium Height
20607 6 Prong Round Setting Tall Height
SH163 ComfortFit Shank for a 6 Prong Setting
20605 6 Prong Round Setting Medium Height
20607 6 Prong Round Setting Tall Height
SH159 ComfortFit Shank for a 4 Prong Setting
20601 4 Prong Round Setting Medium Height
20603 4 Prong Round Setting Tall Height
SH175 ComfortFit Shank for a 4 Prong Cup Setting
20608 4 Prong Cup Setting Medium Height
20616 4 Prong Cup Setting Low Height
SH161 Knife Edge Shank for a 6 Prong Setting
20605 6 Prong Round Setting Medium Height
20607 6 Prong Round Setting Tall Height
SH180 Knife Edge Shank for a 4 Prong Setting
20601 4 Prong Round Setting Medium Height
20603 4 Prong Round Setting Tall Height
SH173 Knife Edge Shank for a 4 Prong Cup Setting
20608 4 Prong Cup Setting Medium Height
20616 4 Prong Cup Setting Low Height
SH155 Knife Edge Shank for a 6 Prong Peg Setting
20604 6 Prong Peg Medium Height
20615 6 Prong Peg Low Height
SH154 Bombe' Shank for a 4 Prong Peg Setting
20600 4 Prong Peg Medium Height
20614 4 Prong Peg Low Height
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Now, I think that I've narrowed it down to one of the following four:
SH161 Knife Edge Shank with 6 Prong Setting
20605 Medium Height
20607 Tall Height
SH155 Knife Edge Shank with 6 Prong Peg Setting
20604 Medium Height
20615 Low Height
Can anyone tell me the difference between the peg setting and the regular setting? Stuller's photos weren't exactly enlightening...
Also, it'd be nice to see the low, medium and tall heads side by side. If anyone happens to have a picture.
Thanks!