Side-by-side comparison showing the Life-Like Proto2000 AAR-B truck on top and the Athearn Blomberg truck on bottom. Athearn made a version of this sideframe but compressed it to fit the shorter wheelbase of the Blomberg truck. The Proto2000 truck follows the Athearn design and uses clones of the same components but replicates the longer wheelbase of the AAR-B truck. I believe Athearn inherited a correct AAR-B truck and sideframe from MDC Roundhouse that was a component of their Alco RS-3 kit, but I don't know that for sure.