You must have an after market torque converter. I have never seen a 300se W126 not have one . I have worked on about 5 in the past.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)