Hi Jerry
if no one has the documents you need then you may be able to piece together the information
from the stepper driver IC data sheets and later Hobbycnc boards like the hobby cnc EZ board
SLA7062M
HobbyCNC ez-M3 Schematic
note - the sla7078m ic's used in the HobbyCNC ez-M3 board have built in 0.155 ohm current sense resistors
so far I've only found a photo of a 4aupc board
the older SLA7062M ic requires two resistors on the pcb see R51 to R58 in the photo
John