it took 12 years but I finally came across some good photos of the Wagenhals electric postal delivery cart

Steve looked these up way back in 2012, https://justacarguy.blogspot.com/2013/09/1913-wagenhals-electric.html

https://forums.aaca.org/topic/341211-period-images-to-relieve-some-of-the-stress/page/626/