Woodward paralleling controls were developped in the late 19 eightteens.
ASG3 was a backpanel synchronizer mounted on a orange metal plate
replacement was ASG4E3100
ASG410 up to serial number <38495
had a aluminum frontplate with white push buttons
After the ASG410+ was launched with minor differences in wiring. plastic foil frontplate and pushbuttons criss-crossed.
In 2001 Leonhard-Reglerbau was merged with Woodward and the ASG410+ Line was converted into SPM-D
In 2016 the SPM-D2 was introduced which is a 1:1 drop-in replacement
ASG4 & SPM-D replacement partnumbers can be get here: