Deturboed GP20's

[parkerlocoworks]

I'm getting ready to start a project to build two of Arizona & California RR's GP20's. From what I have found, these started as UP units and were sold a couple time before making their way to ARZC. Somewhere along the line, the turbos were removed and a large filter box was placed on the top of the hood. I can't find any info on the GP20's and the deturbo process in general, just photos of the actual units. I can see a general shape of the filter box in the photos, but unfortunately, no shots of the top.

I'm looking for info and pictures of those boxes and any other info or details that would show these as rebuilt units without the turbo.

I'll be using LifeLike GP20's in N scale as the base for the model. Info for those can be best found at Spookshows N Scale Encyclopedia.http://www.spookshow.net/loco/llgp20.html

Any help or info would be greatly appreciated.

Thanks, Doug