I always put the stands under the axles. 4 stands will be needed, and be very careful when raising and lowering as the Jackstands can kick out when you lift or lower the front or rear.

If possible or practical just lift the axles high enough to get the wheels off the ground. Crack the lug nuts loose before lifting the truck. Unless you have an air impact gun, it is nearly impossible to get the lug nuts loose once the truck is off the ground.