Thanks guys I am gonna just pull the motor. The customer is all bent cause it is very new but what am I gonna do. I did try one of those soft metal inserts for lag bolts and concrete worked for a couple days but EPIC fail. Again thanks for your inputs!!!!

AMEN to that danny k!!!! very poor engines for industrial equipment

I have done this repair before by cleaning back the broken part, building it up with brazing rods, re drilling and fitting a solid type thread insert like the Wurth Time serts. Its a fairly big job and you will need to remove the engine but not as big or expensive as replacing the block.We have had to do it on the 4 cyl, V6 & V8, they are just a very crap design, a bit like the rest of the engine!!

assuming this is a 4.3 and if some of the bolt land is still on the outside of the block there might be something you can do.
(assuming you dont want to do the right thing an "bite the bullet" which would be best.)
it involves notching the block above the starter/ block mating surface and installing a threaded "plug" in the notch. it can be done in the truck but it would be difficult.
i have a freind that races a lot and he has succesfully made the repair several times.
in my experience that problem has always been caused by lack of support on the free end of the starter. usually the bracket is left off because of alignment problems when aftermarket parts are used.

Yeap....what Grumpy said!!!!

bite the bullet, replace the block.