how many mechanic hours to change my rear main oil seal on 2000 Saturn SL2

someone said with 2 wheel drive? its only an hour

Asked by for the 2000 Saturn SL2
The Motor Labor Time Guide reads 7.5 Hrs. for manual trans and 7.8Hrs. for automatic trans.
The Chilton Labor Time Guide reads 8.6 Hrs. for manual trans and 8.8 Hrs. for automatic trans.
I don't know why the hour differnce but the dealership I worked for used the Chilton time guide.