They should be UNC 7/16 and 1/2 sizes. The front one should be the same as the 2 over the rear axle. The middle 3 pairs and the rear-most pair should be the same. Not a big deal if you pull one out of the mount, measure it, and then go get 11 matching bolts, just 3" shorter. Don't forget to get matching flat washers with the new bolts.
Before removing the 3" body lift, take a look at your rubber mounts. MTL, you'll need to replace these as well. Might as well toss in a poly body lift mount in its place. New bolts will come with it, but the lift will be 1", 1.25" or 1.5" of your choosing.
When you put in new bolts, use antiseize on the threads.