On my 1991 VOLVO 240, The adjusting bracket is attached to the engine block by a bolt through bushings (Dealer says). I got this bolt from the Volvo dealer but I see little hole in the engine block but no threads in this hole. Is it normal?
How many rubber bushings, Metal spacer, for this Adjusting bracket?

the alt. bracket bushing has a hole in the center for the bolt that attaches it (the bracket itself) to the block. put the bushing in the alt bracket, slide the bolt in, and fit it to the block. easy as pie.
--
VX, adj. cam gear, new head, trans cooler, stainless brake lines, electric fan, fully braced, IpD sways, poly bushes, Bils, boxed front & rear arms, lowering springs, 16" Perfos, 25/32mm adapters, 100% zero miled, and much more

You did not understand my question. The engine block has little hole where this bolt will go. Unfortunately this hole now has no threads in it so that this bolt stays. This bolt falls down. I think either old bolt broke in it,or I do not know
Tell me the engine block has threads for this bolt (what size)?

I am not sure how long the alt bolt (to block) is.

check and see if she goes all the way in by hand. you may have something broken off in there.

your only alternative for no threads or a broken bolt is a drill & tap
--
VX, adj. cam gear, new head, trans cooler, stainless brake lines, electric fan, fully braced, IpD sways, poly bushes, Bils, boxed front & rear arms, lowering springs, 16" Perfos, 25/32mm adapters, 100% zero miled, and much more