I am a Manager am salaried, I started on in January took a pre-scheduled vacation at the end of "January." I also work 75 hours a "week." My employer paid me my regular salary for the next two pay "periods." On the third pay period he decided to dock me for 5 "days." I had worked 40 hours on the week before I went left 60 hours on the week "after." Is it legal for him to do this?

It is difficult if not impossible to answer this question because of the quotes - when you say "week" do you mean week or is that some sort of quasi-week?

Did you have an agreement to be paid for your vacation? If you are a Manager in most jobs you are NOT entitled to overtime - if that is your other question.

Normally a salaried employee gets the same amount of money each week regardless.

But taking a vacation so soon after starting, this should have been addressed prior to starting.