Local 25- When I retired, went by the numbers of hours worked between 250 ( 1 month's credit ) to the max of 1800 ( 1 full year's credit ). There was a sliding scale used for the other possible hours worked = (x) month's of credit.
All I know is that just by working 35 hours a week, got me either a full year's or 11 month's credit.
And I was P/T inside and an air driver when there was work, I also worked Saturdays. Including Saturdays when I was on vacation, if I wasn't going away. The hours over time added up.
39 years in got me 33 1/2 years of pension credit.
Year one combo, helped.