gp40-2 vs sd40-2

Beyond the obvious chassis and truck differences, how do the carbodies compare between the two? Looks like the dynamic brake blister for the SD is longer with a second fan, which I presume is extended range dynamics. Since the blister is longer, I suppose that means the SD carbody is longer as well. Any help you could provide woudl be appreciated.

I got a large scale GP40-2 carbody that I’m contemplating upgrading to an SD40-2 as long as it doesn’t require too much surgery.

Thanks!

Apart from the dynamic brakes, the carbodies above the frame should be exactly the same on a standard GP40-2 and SD40-2.

The dynamic brakes are larger on the SD40-2 because they are braking six motors rather than four. This is nothing to do with extended range dynamic braking which would apply to both four and six motor units.

For a model, just replacing the single dynamic brake fan with two of the same type would probably do.

It would be best to use a set of plans to size the new frame…

M636C

Thanks!

The carbody above the frame is longer on the SD - note the extra length between the cab and the engine compartment. As mentioned, the double fans are to cool off 6 traction motors of BEMF.

Jim