Diesel locomotive weight? - Trains Magazine

If by "end plate" you mean the pilot plate...on GPs and the rest of the road switcher designs, 1" thick and up is the norm...on anything used in yard switching where by-passed couplers happen on a regular basis you better have a thick pilot plate...and I would suspect the railroad who’s locomotive where the round concrete plug was in the short hood used that to replace the old steam boiler for passenger car heating, and they were trying to keep the weight displacement on the locomotive pretty close to what it was when they had the boiler in there.

I have been on SD40s, SD40-2, GP30s, GP9, GP7, MK1500D, MK2000Ac, GE Dash 9s, GE Dash 8s, B30-7As(cabless B30s) and the new GEVO units, MK5000, GP38-2, SW7, SW9, UP's SW10, Amtrak Genesis units, the UP’s E9s, (pretty neat rebuild inside), the UP3985 Challenger, an BN SD9, and SP SD9, along with an assortment of F units, and several of the Santa Fe Cleburne CF 7 rebuilds, which were the only units where the addition of steel was obvious, due to the structural modification when the car body was removed and more support was needed.

None of them had sandbags, extra steel, or concrete added.

On the other hand, almost every yard slug I have seen has had concrete added where the diesel engine was removed, to keep the weight for tractive effort, or the fuel tank filled with sand if it was just a slug unit.
UP has three slugs working Englewood with the fuel tanks filled with sand.
They also have a pair of road slugs, with the diesel units intact, looks like they were built on older GE frames...those have ballast weights in the form of huge sand boxes added to replace the missing weight when the hoods and cabs were removed.

With two decades plus of wheel slip technology already in use, the need to "add weight" is long gone....Most of the GE Dash series have excellent tractive force balancing systems, even our simple MK1500Ds can slack off or juice up individual traction motors to prevent wheel slip.

Ed