One of the biggest challenges facing a railfan photographer is the correct identification of one manufacturer's "critter" locomotive from that of another competing builder. The task is increasingly more difficult given the strong resemblance among models, regardless of manufacturer.

The purpose of the Critter Notebook series is to delineate specific "spotting" features of different critters, thus making the challenge less daunting and more enjoyable. So far, spotting tendencies have been completed for General Electric's 44, 45/50, 65, 70 and 80-ton models, as well as Off-Center Cabs. Other GE and Brand "X" profiles will be completed at the rate of one or two per month. The focus of new spotlights for the foreseeable future will continue to be on medium-size (40 to 75-ton) and large-size (80 to 110 ton) industrial / military switchers.

Generally speaking, no effort has been made here to include smaller diesel locomotives due to their high-degree of customization, especially those built for the mining and steel-making industries. Please note also that several GE and Brand "X" models had many dfferent iterations / phases during their production runs; consequently, the basic model often experienced subtle changes. The description of changes associated with each specific carbody phase is beyond the scope of these photo essays. Jay Reed's guide to Critters, Dinkys and Center Cabs is highly recommended for those interested in that evolution.

• Chain-driven Truck
• Davenport 45-Ton End Cab (with roster)
• EMD Model 40 (with roster)
• Vulcan 45-Ton End Cab (with roster)

• GE 45/50-ton Ownership Tracker (table format)

• GE 45/47 & 75-ton Drop Cabs (table format)