here is a great spec web sight from detroit on the 1998 mustang
Mustang engine spec page
and i like the 4.6 better i have driven the 5.0 alot and the torque comes on to low i always found it hard to keep traction off the line with the better power band and higher reving 4.6 i get better performance and save on tires either are great engines i just like the mod better