The armature is also different in a high stack vs a normal stack motor. Its thickness matches the extra thick field set up. Lionel also balanced them to a higher tollerance, along with line boring the motor bushings to assure straightness(like is done in a high quality auto engine rebuild). This assured an extra smooth, cool running motor to showcase the model and minimize break downs on a display layout that would see trains running for hours on each day, especially during the holiday selling season. AD
Such a great engine. Almost had one. Reminds me of my dad and my start into O Gauge. When I inherited my grandfather's (mom's father's) postwar collection in 2002, my dad helped me get started setting everything up. He told me the collection lacked a Berk and I needed to have one, so we went down to the Trading Post Train Shop, my first meeting with Jim Berilla, with purpose of buying a 746. I was all conventional at that point, of course, and we looked at some of Jim's PW items, and I almost bought the 746 my dad wanted me to get (his favorite from his childhood). Then Jim introduced us to some modern conventional items with Railsounds. I walked out with a Lionel NKP Junior Berk and a Santa Fe FT Passenger set. I've since upgraded the Jr. Berk to TMCC and replaced the conventional single FT with AA's with TMCC.
Its never to late to own a postwar Berk, either the 726 or 736. Last I looked, Trainworld out in NY has a small postwar collection up for sale on their website that has a early model 726 and a 736 Berkshire for sale. AD