Where Can I Find USPS Employee Salary + Overtime?

So I know that you can lookup USPS employee salary like from websites below:

However I want to lookup employee salary+ what they made in overtime?

Reason I’m asking is that I’m looking at custodial jobs but would like to know what facilities basically offer unlimited overtime,

the answers I’ve been getting from HR and interviewers is very generic I.e they usually state they offer overtime based upon availiability…