generator tech

I've been going through a couple crates of generators, having trouble identifing armatures, two are obviously fan cooled one having longer commutator bars.
yet another armature has a short comm end shaft, just bearing journal and male threads.
these all have longer wire laminations than the 32E or 65,65A
Are these model 51, 58R or a police variety?
What model used large field coil and a
twisted {off center line} face on pole shoe?
Any one know of a pub that covers all the changes over the years?
don

[This message has been edited by don (edited 20 June 2000).]

[This message has been edited by don (edited 20 June 2000).]

Rene, I have a transition armature,
Same comm. end as the 32E no fan, with long winding laminations as the 58R with the ratchet drive gear setup.
maybe some one cut down the fanshaft, but looks original no weight removed in balancing as 58R's have.
don

[This message has been edited by don (edited 22 June 2000).]