No, Chevy converted to a coil spring suspension for their GMT-900 trucks. (07 - 10)
YES it does.
Yes.
No, The Silverado 1500 does not have torsion bars it has coil overs and shocks. All 4wd silverados have them and the 2500HD 2wd also does.
Take the truck to your local Chevy dealer and have them adjust the torsion bars to lift the front and then do a realignment. About 100 bucks. New torsion bar keys are not needed.
You must crank the bolts on the torsion bar clockwise to lift the vehicle
Turn the adjusting bolts.
If it 4x4 you need to crank the torsion bars so no rubbing happens but you can easily put 285/70R17
on the rear cross member where the torsion bars mount there is an adjustment screw
No they have a arms with coils
Crawl under the truck. Look at the torsion bars (if you can't find the torsion bars, just take it to a shop and have them do it). The torsion bars will have a bolt at each end; take those bolts out. You might want to have the frame held up with jackstands when you do that, I'm not entirely sure how much the torsion bars are involved in keeping the truck from falling on your face (probably a lot).
jack up front end, drop both bolts out of the torsion keys, knock both bars out then put new keys in
Yes this is true.,,but not all 04 2wd have torsion bars some come with coil overs. I think the HD version are all torsion bars.my truck is 04 2wd extra cab w/6.5 bed.