Spring of 1972 brings Athearn's U33-B and U33-C models to HO-scale. According to Ken Goslett's 1999 Railroad Model Craftsman article, General Electric originally sold the U33-B to only four railroads (NYC, Penn Central, Rock Island, and SCL) with 137 examples built from the fall of 1967 through early 1969.

The Seaboard Coast Line U33-B is good match to the prototype, SCL was even good enough to buy its boats with the nose headlight package that Athearn favored. The Auto-Train is basically correct, though its a U33-B the U36-B that Auto-Train rostered was very similar and did include the dual nose headlight. Athearn also provided what would be road specific trucks in EMD Blombergs on the Auto-Train example. The Rock Island 286 was a U33-B from the Rock's first order in 1969 of two that it placed with GE for this diesel. The New York Central example, roadnumber 2858, represents one of only two U33-B's on the NYC roster. Successor Penn Central would be home to the majority of U33-B production from GE.

The only bicentennial dressed loco in the old Athearn blue box collection was the Seaboard Coast Line's 1776. The HO-scale market saw an explosion of red, white and blue locos during the '70s, next to none being prototypical. Examples including Bachmann dressing its U36-B for N&W's 1776, which was in reality a high-nose SD45. Bachmann does get credit though for the only match of paint and loco with its U36-B done in SCL's tread setting 1776 colors. Athearn would be a close second with its SCL #1776, substituting the nearly identical U33-B for SCL's U36-B. Athearn made two attempts at this model. One features a very light and very incorrect blue with a second offering nailing the blue with much more accuracy. Nobody has to date done the U36-B in SCL 1776 dress complete with the gold bell mounted from the headlights between the numberboards and the SCL originally featured lights along the walkway to illuminate the engine. The nose headlight Athearn included in its U33-B tooling works for the SCL model and Athearn offered its 1776 edition with EMD Blombergs, as per prototype.