Stepperati Mysteriosi

Gentlemen,
I have 3 stepper motors (non-permanent magnet) which I have had for
some time and I could use some help in evaluating them for CNC use.
The Motor Plate reads:
"Motori ed Apparecchiature
Elettriche s.p.a.
Ivrea - Italia
M 41200 - 125D
N = 4 fasi A = 1.3 / fase"
Weight is 4lb (1.8 kg). Length is 2.5 inches. Body diameter is 3.4
inches. Does this make it a "34 frame" ? (By the way; it seems that
NEMA specs are derived from NATO specs. Are these the same here ?)
The 6 wires, and the hand-copied Driver Circuit Diagram (No Driver
electronics) that came with the motors point to it being a 4 phase
monopolar configuration with 1.8 degrees/step. (I assume that the
simple on/off series transistors on each phase winding allow only
monopolar configuration).
I have a scanned image of the Driver Circuit Diagram, and of a few
accompanying roughly-sketched connection sheets, but do not know the
protocol of posting files here, and can't work out how to upload to a
clickable URL anywhere. I can email to anyone obliging enough to help.
The Voltage supply options are 5V ("holding"), 12V ("step") & 38V
("return")! I have no idea what equipment it is from.
(Hmmm... 12V step; 38V return... military equipment ?) :)
I also imagine that the lack of a quoted Supply Voltage on the Motor
Plate suggests that a chopper circuit to regulate current would be
employed, especially since there are series "sense" resistors in the
common legs to each phase-pair (The Driver Circuit Diagram is
confusing on this point: There are two 12 Ohm, 25W resistors mounted
on a serious heat sink on the motor body and 15 Ohm, 4W (2x 30R, 2W
in parallel) in the 12V supply, however, the 38V is shown as being
switched directly through a darlington to each phase-pair common,
connecting without series resistors.) ???
I have no Controller information, but the digital signal names on the
diagram and rough "connection sheet" may be a clue to the Wise.
My dumb questions:
Is the designation on the Motor plate of "M41200" a recogised
specification ? (Sanyo have a similar system). (..and the "s.p.a." ?)
What suitable Driver might be used for these motors (V, I-reg) ?
Would the Voltage of Driver Circuits be critical if a chopper type or
other regulation of current at 1.3 Amps per phase was used ?
What torque & power rating would be expected from the specs given?

The motors also have a Moire-Fringe type pulse-transmitter on their
shaft (180 slots), which I imagine was used in feedback for a closed
loop controller.
What interesting use might this facility be put to ?
Is typical servo feedback of similar signal type ?

Some Members may be encouraged to see my attempts at a "real-world"
project, but I must disappoint them by saying that my MAD_CAM Torque
Amplifier project to which these motors have no connection is coming
along nicely in parallel. :)
Any attempts to keep me on the straight-and-narrow path would be
appreciated.

Cheers. Don.