Model Railroading > SD70, 70M, 75M, 75i, 70MAC: All Different

There seems to be some continuing confusion regarding the above loco models, which cause people to use the model designations interchangably. There are locos out there which have had some accurate variations in there model designations which were the same (such as the 8-40BW, which can also be called a B40-8W), but this is NOT the case with the above locos. This is not counting rivets! These are significant differences. Someone can help out with pictures, but here\'s a basic visual difference overview:

SD70 has a standard "spartan" cab.

SD70M has a wide cab. SP and UP units were/are SD70M\'s. Some SD70M\'s have flared radiators. There were/are no SD70M\'s painted ATSF or BNSF.

SD75M looks much like the SD70M, but has another square bulge on the right flank (engineer\'s) side. ATSF and BNSF ran/run these and are mostly red & silver "warbonnet" (although some are being repainted H2). BNSF umbers are 8200\'s up to 8275. There were/are none in the SP/UP livery.

SD75i is nearly identical to the SD75M, but has an isolation joint in the nose and different sideframes. BNSF runs these in red & silver "warbonnet" (8276 -8301). Again, none in the SP/UP livery.

SD70MAC is significantly longer than ALL the above and is mostly seen behind the radiators. These have an SD60-style blower housing on the left side, not the square one like all the above do. BNSF and BN run/ran these in H2 and "Eddie Bauer". Most of these have the isolation joint in the nose as does the SD75i. The 70MAC is the ONLY 70 series loco that Kato has pre-announced.

Hope this helps! : )

Russ

tehachapifan wrote:

> SD75M looks much like the SD70M, but has another square bulge
> on the right flank (engineer\'s) side. ATSF and BNSF ran/run
> these and are mostly red & silver "warbonnet" (although some
> are being repainted H2). BNSF umbers are 8200\'s up to 8275.
> There were/are none in the SP/UP livery.
>
> SD75i is nearly identical to the SD75M, but has an isolation
> joint in the nose and different sideframes. BNSF runs these in
> red & silver "warbonnet" (8276 -8301). Again, none in the SP/UP
> livery.

Don\'t forget that CN has SD75I and SD70I as well.

> SD70MAC is significantly longer than ALL the above and is
> mostly seen behind the radiators. These have an SD60-style
> blower housing on the left side, not the square one like all
> the above do.

DC SD70s do not have a blower bulge. That is an electrical cabinet on the conductor\'s side behind the cab. This is because the units use two blowers -- one for each truck, instead of one blower for both trucks like units with blower housings.

Thanks, Russ. Great overview.

We can also add the SD70I, which is an SD70M with the isolation joint in the cab nose.

Also, the SD75MAC doesn\'t exist, even though some BNSF SD75Ms were mistakenly labeled as such. Real SD75MACs are actually named SD90/43MAC. :-)

Markus

starlight wrote:

> Also, the SD75MAC doesn\'t exist,

Ha, that\'s why I chose SD75MAC as my screen name. Cause they don\'t exist

http://www.phcomputing.com

For reference, here\'s Ontario Northland\'s SD75i...

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Kato sites the difference in the Phase I SD70MAC and the Phase II SD70MAC (trucks I think) for not planning to produce their model in Burlington Northern paint. The BNSF Executive paint can be used as these are phase II. Can someone tell me the specific differences in Phase I and Phase II?

The first few series of 70MAC\'s that BN took delivery of had the original HTCR (Ph 1A.)truck that EMD produced. It is the same truck that Athearn has used on their SD70 Series locomotives. The Phase 1B, is the same as the Ph. 1A. but with the snubber offset from the center of the bearing and the roller bearing cap is exposed.

The HTCR Phase II is only available on the SD80/90MAC, it is physically larger and heavier than the HTCR 1B, though they look almost identical.

The version of the SD70MAC Kato is going to produce has the Ph. 1B trucks, 5 steps in the stairwells and high mounted headlights, BNSF (2 schemes), CSX and Conrail (and all subsequent patches and re-paints). ARR and the 8800 series BNSF\'s had low mounted headlights (maybe future release from Kato???) The early BN\'s had Ph.1A trucks, 4 and 5 step stairwells and high mounted headlights.

You probably will be able to graft the Athearn sideframe onto the Kato truck, by replacing the mounting lugs. Don\'t know, haven\'t seen one yet, or will for a while.

Sorry this is long explaination, but does answer your question.

NSTopHat

Thanks NSTopHat for the good answer, I\'ve been trying to find the difference for a while. I never was too good at those \'what\'s different in this picture\' things.

Hey, no problem. I thought the HTCR Ph. II\'s were the same as the HTCR Ph.IB\'s, until I talked to a guy at the EMD 75th Anniv. Open House a couple years back. The size of the casting has to do with traction motor and tire size, along with some weight issues. I\'m not sure if the sideframes available from Train Station Products are truely Phase II\'s or if they are Phase IA\'s that were modified into IB\'s.

NSTopHat