4. Abstein (Print Group 2)
An interesting note here, I found an Abstein with a "T206 Harris Collection" flip, hadn't seen that before. I think it was a PSA 8 of a Piedmont 350. Cool.
Discoveries within the Abstein scans:
T206 > Factory numbers: 4 (13 Piedmont 350s)
T206 Sweet Caporal > Factory numbers: 11 (1 that was not readable)