Between the SD70ACe and the SD70M-2, the only difference I know of is in the electrical cabinet behind the cab on the conductor's side. An ACe has two large panel covers with grilles in them, whereas an M-2 has three panel covers with no grilles, just oval hand holes. At least that holds true for the prototypes, I can't speak for production units.

The SD70MAC is slightly longer than the SD70M, as well as having a few SD60-ish features, like the angled blower bulge. The extra length is most apparent in the extra hood length aft of the radiator intakes. As for the UP SD70M controls, they are desktop style, with analog gauges (at least on the couple I\'ve been aboard).-Nameless Modeler

The RA SD70M-2s didn't fit in with FEC's paint at the time, but I always like the red, white and blue, especially if there was a matching pair together. 106 in happier times: 12/28/2009 Jacksonville, FL with train 101, note with the as delivered RA nose herald. 5/14/2014 Fort Lauderdale with train 121, now minus the nose herald.

notch-nose SD70M's have same level flat noses that bo not taper as much with the larger quarter round eased edges. Looking at the nose form the front, it notches down at roughly 90º around the square nose cornered door instead of the 45º tapered upper left corner doors delivered on all SD70M's (except the first EMD Demo's) prior to UP4837.

The SD70M's are good flat land locomotives, when on mountain grades they do not hold a candle to the AC units in power or DB. If you have a train 3x2 DPU with 3 out of the 5 being SD70M DC units you can definitely tell the difference in power and …

FWIW (you may already know), there was an excellent article about doing a UP SD70M in the Sept. 2001 issue of Model RailroadING magazine by Steven Orth. It has six neat B&W photos and three drawings for construction of the flared radiator section using sheet styrene, stock Athearn fans, and a set of Cannon & Co. RS 1407 Rad. Screens, and Cannon ...

If I remember correctly, when UP took over SP, they found most of the SP units--except the SD40M-2's, SD70M's, Dash 9-44CW's and AC4400CW's new in service since 1994--to be in pretty bad condition. Small wonder why UP scrapped many of them and bought over 1,000 SD70M's as replacements.

A very smooth-riding, good-pulling unit quieter on the inside than a straight SD70M, louder of course than an EMD unit with the isolated "Whisper Cab", with the melodious, spine-tingling Nathan K5LLA five-chime air horn. Everything worked perfectly. I like the UPRR's SD70ACes, but found the SD70M-2 to be just as good as an SD70M--I liked it.

> SD70M's? As delivered: 4000 thru 4278 = P3 4285 thru 4384 and 4562 thru 4604 = K5 All the rest = K3 Of course, over time, horns get changed. A few of the SD70Ms now have Leslie S3s, and some of the others have been swapped around with various Nathans.

I am trying to find the definitive lenghts of each of the loco types listed. I have found conflicting information. Can anybody please confirm the lengths. Many thanks for reading. US railfan