Without going into a long explaination, does anyone know if this is an easy swap? By easy, I mean without major (even minor?) surgery. Also, any suggestion for a good sound decoder that would nicely fit after the marriage?
A little clarification on what brand shell you want to put on what brand chassis would be helpful.
Check this link out:http://melvineperry.blogspot.com/2011/08/atlas-gp-9-basket-case.html
This guy put an Athearn shell on an Atlas chassis if that is what you're asking.
It will be easier to recommend a decoder/ speaker after seeing how much space you have left.
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More info is needed for sure. If you want to keep the Athearn unit, and swap in the Atlas drive, that can probably be accomplished without much trouble. Due to the design of the shells and frames, a body swap may not be especially easy, but that depends on what you're contemplating. Atlas used a separate hood/cab assembly mounted onto a metal frame that included walkways, steps, fuel tank, etc. Athearn, both the old blue box and newer Genesis, has a plastic shell, including the walkways and steps. While I haven't investigated it, substituting an Atlas hood/cab for the Genesis components might be fairly simple since the Genesis model also has a separate hood/cab.
This photo may help:
It shows an old Athearn blue-box GP9 on the left, and a new Proto GP9 on the right. The significant difference is the width of the hood. The older blue-box models were significantly oversized, because they used large motors that would not have fit in a proper scale model.
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Thanks to the thoughts. I am hoping to put custom painted T&P orange/black bodies on the quieter and smoother running Atlas chassies. I'm now thinking I may simply add decoders to the Atlas locos since they are painted in the orange and black as well.
Anyone have experience with a easy fit sound decoder for the Atlas?
I don't know about fit, but the Soundtraxx Tsunami GP9 decoder is really nice. I put one in a Proto GP9. It took a lot of surgery, cutting out weights for both the decoder and the speaker, but the results were very good.
mreagantI am hoping to put custom painted T&P orange/black bodies on the quieter and smoother running Atlas chassies.
If that's the case, you could be able to drop the Atlas drive components directly into the Athearn frame. Check the fit of the Atlas motor mount and the Athearn frame to ensure it will screw into place. I suspect the Atlas GP7 drive is a clone of the Kato drive in various Stewart and other Atlas locos, in which case it may mount into the Athearn frame like it was designed to. I've done a number of mechanism swaps of Kato drives into Athearn frames and they are generally very easy.
I'm now thinking I may simply add decoders to the Atlas locos since they are painted in the orange and black as well.
Given the overall better quality of the Atlas model, this does sound like the preferred option unless you're really intent on using those Athearn shells.
Several companies make motors to retrofit into an Athearn diesel, check out the Walthers website or catalogue.
Sometimes just converting the Athearn engine to DCC will help, as adding Back EMF will make it run smoother up and down grades.
I have some F-unit A-B sets where one unit is powered with a Athearn chassis and motor, and the other is from Stewart or Athearn Genesis. Combining the Athearn one with the better running one, and speed matching them together, does seem to work pretty well. You could try running one Atlas and one Athearn GP together and see how it works.
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