The proposed Saturn IB-B was to be essentially an uprated Saturn IB using the new MS-IVB-2 upper stage, using the HG-3 engine, developed from the S-IVB and an uprated S-IB-A first stage.

v t e Saturn launch vehicle family
Early proposals	Juno V Saturn A-1 A-2 B-1
"C" series	Saturn C-1 C-2 C-3 C-4 C-5 C-5N C-8
Saturn I series	Saturn I IB IB-CE IB-A IB-B IB-C IB-D INT-05 INT-11 INT-12 INT-13 INT-14 INT-15 INT-16 INT-27 LCB
Saturn II series	Saturn II INT-17 INT-18 INT-19
Saturn V series	Saturn V MLV V ELV INT-20 INT-21 INT-23 INT-24 INT-25 Saturn-Shuttle Saturn V-3 V-A V-B V-C V-D V-Centaur Jarvis