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.
| Early proposals |  | |
|---|---|---|
| "C" series | ||
| Saturn I series | ||
| Saturn II series | ||
| Saturn V series | ||