What would cause a jeep wrangler steering wheel shake at 49 mph and i have changed the steering stableizer shock?

Warped or out-of balance brake rotor? Also keep in mind that loose rear differential trailing arms that allow the rear differential to squirm around can also cause steering wheel shake.

If it shake only when the brakes are applied, then it is a brake issue/ uneven wear on the pads & discs.
There are upper and lower control arms, but if they are bolted tight, it shouldn't be the issue. If you hear clicking, check out you CV joints.
Have you rotated you tires? Patterns can wear in and cause lots of shaking.

There is a steering dampener underneath that looks like a strut or shock absorber. Replacing this should correct the problem.

You may have rotated imbalanced wheels from the rear to the front .Its possible not to feel the imbalance from the rear as it is far less sensitive and not transmitting through the steering wheel. Check tire balance or move the tire back to their original position which might help veify the source of your imbalance.

could be a bent rim ? have you changed the universal joints? how about the tie rods and stabilizer bar

Good excuse! You need to find a shop that does alignments and have special attention to caster. However, did the shake happen from when you first got it or did it develop over time? Check all front components for wear (by all I mean all) especially ball joints and steering damper (the sideways shock on the linkage) All can cause this condition.

make sure the steering stabalizer shock is not blown out(leaking), or a seperated tire.

Shocks are usually pretty much shot after 45-50K. Also check damper (sideways shock on steering linkage). Shake is either wheel balance or a worn steering component (should have been checked before alignment...shame on them if they didn't)

My Death Wobble started immediately after I installed a set of Coil Spring Spacers (to lift 1.75 inches) on my 2005 Jeep Wrangler X. Turned out, the DW was because while changing the height, I also lowered the CASTER angle in the front end. So, to fix it, I could have purchased a set of eccentric bolts for $50+. Instead I went out and purchased a piece of 1.5 inch flat bar for $10 from OSH. I cut out 4 1.5 inch squares. Then i drilled 7/16 inch holes centerline, but close to one side (in exactly the same place) on all for squares. I then removed the lower control arm bolts, nuts and washers. I installed these square offset washers I made so the front axle would be pushed forward (to increase the Caster angle). The toe setting changed a bit, so I reset them to about 1/8 inch toe in. After driving my Jeep, I noticed there is no more DW. The steering wheel was off center, but after 3 attempts, I have that perfectly centered. I have every intension of having the alignment checked, but not till after I find the new tires I want. If anyone is interested, I can draw out and photograph the cure and send it to you. My e-mail is bb62471(at)yahoo(dot)com.

my jeep had the same problem. it was the shocks going bad along with the steering stabilizer. all easy to replace and costs about 170 far all the parts. search how to replace shocks jeep grand cherokee on google if you need more help on replacing them. i got my parts at autoanything.com (free shipping)