Get yourself a large breaker bar and the right 1/2 drive socket, 12 point if you've got it.
The longer the lever, the more leverage you have, careful you can pull the truck right off the jackstand.
If that doesnt work a 4" grinder and trip to the hardware store for new grade 8-10 bolts will make short work of those suckers. ON a job like this I hardly ever re-use the stock hardware, but then my trucks got 240K miles so those suckers are not coming off easy......
When you know you are going to tackle bolts like these, 3-4 days ahead start using the liquid wrench and let it soak for days, also always be prepared to cut or replace, especially if you have to be at work mon morning........ hehehehe even a "simple" adjustement can turn into a week long affair...........