The SUD conversion was ordered by 3 airlines: KLM (10x 747-206Bs converted), UTA (2x 747-2B3Bs converted) and JAL (2x 747-146Bs converted), making a total of 14 747-100/200S converted to SUD.
It's interesting to note the history of KLM's PH-BUH and BUI. Born as regular's 747-206Bs, they were converted to SUD, and then to Freighters SD...making them the only SUD and Freighter converted 747s.
Just for the record. The PH-BUL and the PH-BUK haven't been retired because KLM has retired the PH-BUP and the PH-BUR will be retired at the end of the summer schedule. Moreover, KLM seems to have some difficulties in selling both the BUK and the BUL as they are old and have a lot of flying hours and cycles.
PHBUH Converted to freighter
PHBUI Converted to freighter
2 freighters, 6 combi, 2 all pax.
Pretty interesting topic. After looking through Bill Harm's the only other carriers to have the SUD coversion done were KLM, who had all of their GE powered 742 converted, and Air France (presumably these were ex-UTA planes) who has 2 747-2B3-SUDs. The JAL 747SR-146B-SUDs are JA8170 and JA8176... both delivered in 1986, which has to make them the younger 747-100s out there. ANA also has two.