Diesel locomotives were often rebuilt to extend their service lives and fix teething issues that came up due to aging of locomotives. Rebuilding was less expensive than purchasing new locomotives. The rebuilds had upgraded electrical systems, controls, and many times, even new or upgraded prime movers. For example, the Burlington Northern RR rebuilt some of their ex-CB&Q E8 and E9 passenger units in the 1980s for service on Chicago commuter service. The rebuilt engines had upgraded systems and single EMD 645 prime movers replacing the twin 567s on the original units.
Lionel and MTH have some rebuilt diesel loco models, but they are not exactly accurate to the real locos. I'd like to discuss some of the more common rebuilt diesel locomotives and how Lionel, Atlas, and/or MTH could make accurate models of them. 3D printing would be a possibility, as would more modular tooling.
1.) BN GP39E/M/V and BNSF GP39-3:
As a BNSF RR modeler, these locos would be great to see made. In the 1980s (around the same time as the rebuilt BN E-Units mentioned in the intro above), BN decided to rebuild many of their GP30 and GP35 units (and some from other RRs, too) which, while good locos, had some electrical issues. BN worked with EMD (GP39E), VMV (GP39V), and Morrison-Knudsen (GP39M) to upgrade the older Geeps into the equivalent of EMDs 2300HP GP39-2s. Some of the GP39s had new EMD Spartan Cabs, especially the GP30 rebuilds). BNSF in the 2000s further rebuilt their ex-BN GP39Es/Ms/Vs, along with many their ex-ATSF GP30u/GP35u locos, into GP39-3s with modernized control and electrical systems. Lionel and MTH both have GP30 and GP35 toolings. With a few modifications to the radiator sections, they could do fairly accurate GP39 rebuilds, especially the GP35 versions. The modified GP30 versions would require new tooling of the body shell.
2.) NS Admiral Cab and ECO Rebuilds:
NS has been rebuilding many of their SD40-2s and GP40-2s with modernized controls and electrical systems over the last few years. These upgraded units have also received new cabs designated "Admiral Cabs" because the front windows slant upward like a Navy warship. The cabs were designed by a former US Navy Admiral who worked for NS. They have increased crash protection.
The NS Admiral Cab would be something Lionel or Atlas (ex-MTH) could add to their SD40-2 toolings. The only thing needed for these upgraded SD40-2s would be the new cab tooling. Everything else is stock. Atlas has MTH's GP40 tooling, so with a few modifications to the tooling, they could do an Admiral Cab GP40-2.
NS also has GP33ECOs (rebuilt GP50s and GP59s with SD45-style flared radiators) and SD33ECOs (rebuilt SD40-2s with SD45-style flared radiators) with the Admiral Cabs. These would need new tooling (MTH does have a GP60 tooling; the GP59 has the same body as the GP60 with a smaller 12-Cylinder 710 engine) for the radiators and cabs. Same with the SD33ECOs. I don't think anyone has a GP50 tooling in 3-Rail O-Scale. Correct me if I'm wrong.
3.) SD70 Rebuilds: NS SD70ACC and NS/CP SD70ACu:
NS rebuilt 52 of their older SD70 Spartan Cab units into SD70ACCs with new wide cabs and AC Traction Motors, along with new controls and electronics. When Lionel did their version of these, based on their SD70MAC tooling, they didn't do the front nose correctly. The nose of these engines should look like an SD70ACe. I think MTH's version was incorrect, too. (of course, Atlas has the MTH SD70MAC tooling now).
NS and CP Rail rebuilt ex-UP SD90-43MACs into SD70ACus with upgraded systems and SD70ACe-style cabs. While both MTH and Lionel have SD90-43MAC toolings, neither company the cabs right on their SD70ACu models.
4.) CSX SD40-3, GP40-3, and GP38-3:
Another interesting rebuilding program was for CSX's many SD40-2s, GP40-2s, and GP38-2s. CSX upgraded the electrical and control systems of many of their Dash-2 diesel locomotives, giving them a "Dash-3" designation. CSX also added a new cab design with increased crash protection. The boxy cab design has been dubbed the "Spongebob Cab" by some railfans (or so I've heard).
Besides the new cab, these rebuilds would be basically the same as the original SD40-2s, GP40-2s, and GP38-2s. Lionel and Atlas (former MTH) have SD40-2 tooling, so all that's needed is the new cabs. Atlas's former MTH GP40 would work with a few modifications for a GP40-3. MTH has a GP38-2 tooling, so that would work for a GP38-3.
5.) CSX ET23DCM/SD23T4 (SD40-2 Rebuild):
I know what you're all thinking: "Not another SD40-2 rebuild idea." Well, this one is a bit different. CSX recently had 15 of their SD40-2s rebuilt with 6-Cylinder Wabtec prime movers and massive SD70ACe-style radiator sections. Yep! You heard that right: an EMD loco rebuilt with the prime mover of the competing company, Wabtec! The ET23DCMs (designated SD23T4s on CSX) are EPA Tier 4 Compliant locomotives.
I don't think Lionel or Atlas will ever make CSX's SD23T4s. This loco could be a good canditate for either Lionel's Brass Hybrid Line or Vision Line, though. If someone wanted to make a custom model, they could 3d print a new radiator section for an SD40-2 and modify the shell to fit it. Then they would just need to find some way to get the sounds correct for the 6-Cylinder Wabtec Prime Mover (A Blunami Decoder or MTH DCS Decoder with custom sound files might work).
6.) Rebuilt Modern GE Locomotives:
Wabtec has been rebuilding locomotives recently for all the Class 1s. NS has been doing the same thing with some of their older GE locos. Let's talk about each of these in detail:
-NS AC44C6M: NS has rebuilt the majority of their older C40-9 Narrow Cab units, C40-9W Wide Cab units, and C44-9W units with GEVO cabs, AC traction motors, and upgraded systems. MTH has tooling for an AC4400CW and has made these locos. Lionel does not have an AC4400CW tooling yet. Will they make an AC4400CW model in the near future?
-UP C44ACM: Wabtec has been rebuilding many of UP's AC4400CWs as C44ACMs. UP's C44ACMs are the same as NS's AC44C6Ms. Also, they have been rebuilding many of UP's C44-9Ws and AC4460CWs/AC6000CWs as C44ACMs. Both Lionel and MTH have AC6000CW tooling.
-CSX (CM44AC/AH), CP (AC4400CWM), CN (AC44C6M): CSX, CP and CN also have AC44C6Ms rebuilt by Wabtec.
-BNSF AC44C4M: BNSF rosters 20 of these rebuilt C44-9Ws (#s 599-619). They have the same cabs and systems upgrades as the C44ACMs/AC44C6Ms, but with 4 traction motors similar to BNSF's ET44C4s/ES44C4s. While MTH has recently announced a new run of AC4400CWs and one of the models in the run is a BNSF AC44C4M, the trucks don't have the accurate details like Lionel's new BNSF ET44C4 models.
