Difference between U33C, U34CH, U36C?

Besides the obvious that the U34CH was for passenger service, and had the larger red marker on the nose. Are there any other exterior differences between the 3?

and a lil off topic, does anyone have a guestimate as to many 6 axle uboats are still around?

The U34CH's HEP generator forced a relocation of the equipment blower: it therefore lacks the air intake high on the side of the long hood just behind the cab that all other U-boats have. Otherwise I don't know of any consistent external spotting marks.

Lake Superior & Ishpeming might still have some U30Cs. Probably not very many at this point. One of LS&I's U23Cs is supposedly in a museum or preserved somewhere.

There might still be a handful of U34CHs and U36Cs in Mexico.

Six-axle U-Boats are definitely a rare breed nowadays. You're more likely to run into a U23B, many of which seem to have nine lives.

The Lake Superior & Ishpeming does have some U30Cs.

There are some U33C in China... heavily rebuilt: maybe better described as ex-U33C. See "The GE locomotives what model?" string on this forum for some details and link to photos.