does my 2004 F150 with the 4.6 have the 28 spline axle or 31 spline
and what would be the best locker for the buck. i do mostly pavement driving but i want something that when i go threw mud and snow i wont get stuck

 

if you do mostly highway, i would go with a good posi unit over the locker, squealing tires around every turn is annoying after a while and a lock on snow can spell disaster in the right conditions.

 

thx for the advice what spline of axle does my truck have