I just replaced one several months ago for a Sterling and bought the part at FLT of Knoxville. Price was 31.50.
I had to take a fuel tank cover off and install. It took about a half hour.
Probably could have went underneath but I didn't want to get dirty.
Fleet owners aren't suppose to get dirty

Dealer needed several hours before they could get it in so I did it while I was there with the driver.
So figure the parts price and 1/2 hour of labor unless it is difficult to get to.