Yup, quite complex calculations in there, especially when out of school for 20 odd years.
The steppers I have were purchased from Oatley Electronics about 8 years ago. The details from the label are:
C35M048A03-X
12VDC 155ohm
7.5 degree Ratio 1350:1
Hope that's enough to go off as that's all that's printed on them.
cheers
Damien