Union apprenticeship sign-ups near Oklahoma City - what worked for you?

I heard of an apprenticeship with paid on-the-job training for people changing careers. Any experience at all would help. Classes are in the evening and work is during the day. Did anyone go through it?

The aptitude test was mostly maths and reading a diagram. Free practice tests online were enough for me.

You earn while you learn, but the first year is tight. Plan your budget carefully.