If you have seniority.. which I suppose you do, you should get paid your normal rate.
When I was a driver, from time to time after I qualified, I was asked to come in on
preload(asked if I would, never required, unless your the bottom guy)
I would get paid my drivers rate on the belt... sometimes payroll would make
errors and try to adjust my payrate, but my center manager would make the appropriate adjustments.