If I recall correctly, Z74 and Z75 are thought to be phyloequivalent; but as Z75 is not offered by FTDNA, I couldn't test this hypothesis. Additionally, my understanding is that S297/Z718 (and Z720 which hasn't really been tested at all) was also thought to be phyloequivalent to S436/Z719/L813. Furthermore, I've dug through the 23andme data for both me and my father and found that we are L277-, which should suggest that L277 is downstream of Z74. Are any of those CTS series SNPs you list synonyms for Z2338? We have Z2336=CTS6364 and Z2337=CTS10028. It'd be great if Z2337 and Z2338 could finally be placed with some certainty.