Rail industry. Apparently, some ships use the same diesel engines, generators, motors, and switchgear as diesel-electric locomotives.
The knowledge base translates well to this particular civilian industry.
One thing I have noticed is that the leftism is inversely proportional to age. The people who had 20+ years in the military, down to about 8 years are much more conservative than the the ones who only were in for 6 years or less.
Also a factor is where these people were originally from.
It might just be that the kind of people who go into the military for the job skills training (engine repair, etc) are not the same as the ones who go into the combat-arms sectors.