Is it my imagination, or do the two AC4400W's on this picture have different thickness radiators? Jeremiah sent me a high-res version of the pic, and it sure looks that way. The lead unit has two dynamic brake "breathing holes" while the second unit has three, so the two units are different in that respect. Could it be that a thicker radiator is another spotting feature of the later model AC4400W? Perhaps Doug or another of the hawkeyes in the group can shed some light?
The trailing unit, UP7029 is actually a 4400HP convertible version of GE's AC6000CW. They have been called many things, but I have seen C60/44AC used the most. It shares the 4400HP prime mover of the AC4400 in the carbody of the AC6000. This is the reason for the different radiator appearance. In case you looked at a current roster and are saying "UP7029 is an AC4400", here is an explanation: UP's C60AC's and C44/60AC's (their designations) were originally numbered 7000-7079. They were renumbered at a later date with the 6000HP units getting 7500 series numbers and the 4400HP units getting 7300 series numbers. For more UP roster details, follow the link below. I hope this answers your question... http://utahrails.net/all-time/modern-index.php
