You can buy them at chevy dealer or PATC on line and word of the wise the front drive shaft need to be shorten up at least 1 inch when GM built the cucv and civi Chevy K30 or K35 GMC all the trucks and k20 k 10 and so on the front drive shaft was to long and the front leaf springs was to weak and or the truck was out fitted with a snow plow and so on.
It was a common repair even with tork bar in place it eather would blow the T case or so on and an adapter or transmission case busted.
I had to do repairs in the 83 - 85Chevy or GMC out fitted NP208 at the maint shop.
also if your front springs are neg arch look to see if the bumper block been in contact or if you have less than 4inch to the bumper block it out of speck.
As most of the cast iorn been busted the truck may have been fork lifted and stress the adapter and if it was broke on the top of the adapter it was droped and or sever off road abuse.
