The SD30C-ECOs have been delivered in two batches:

the first batch was comprised of unit numbers 5000-5019 (delivered in 2013) and the second batch included units 5020-5049. (delivered in 2015/16)
All of the SD30C-ECOs were rebuilt from “donor” SD40-2s and were given brand new pilots, fuel tanks, cabs, and noses, but retained the frames, steps, and trucks of their donor units. (as well as a great deal of the internal mechanical parts) The long hoods of the donor units were cut up and some components were spliced into the rebuild construction, so the rear-most section of the long hood containing the cooling fans and angled radiator grids is all new material but the section of the long hood between the rear wall of the cab and the back of the DB blister is retained from the donor unit. This means that there are several variations of exhaust hatches and traction motor blower ducts depending on which class of SD40-2 the donor unit came from. Most units in both orders were built from Canadian donor units and have GMD ladder-style steps and end platform handrails, but there are a few units mixed into both orders that were built from American donor units and have the angled steps and handrail profile characteristic of La Grange-built SD40-2s. Despite the unit-to-unit inconsistencies owing to the varied classes of the donor units, there are (luckily) a few spotting differences that are consistent between the two batches of rebuilds.
Units 5000-5019 are not locotrol equipped and all feature a single tubular “radome” on the cab roof that encloses all antennae. (GPS, EOT, and radio) All units from this order have standard road numbers but no additional information or lettering on the cab sides. Horns are mounted on top of the conductor’s side of the long hood just behind the DB fans, and the bells are located under the frame on the conductor’s side, just ahead of the fuel tank.