i put the jack under any solid point without concern, including the pumpkin, axle tube, shock mount, suspension arm mount, knuckle, frame, hitch, etc.
my most common points are pumpkin or u-bolts in the rear, and suspension arm mounts in the front. due to the offset pumpkin, the front doesn't have a single good balance point.
if you're getting under it in any way - always use heavy duty jack stands, perferable under the axle tubes. - which forces you to place the jack in a different spot than where you put the stand.
ALWAYS BE SAFE.
another little tip - when you remove the tire, and have to put it somewhere... slide it under the truck underneath some structure. if something fell, it might save you.