GMC Repair: belt replacement, gmc suburban, belt tensioner

Question
I have a 93 GMC suburban with the 350-
i went to replace the main (only)belt yesterday and busted two socket wrenches attempting to free up the tensionor. Am i missing something?  why is it so tight?  I tried a bit lock easy on it still nothing?  I can't move the nut at all- right or left?  Is it just froze?  If so how do i go about removing it to get a new one-  

Answer
Hi,Chip

 The belt is retained by the belt tensioner it is located on top center of the belt,use a 1/2 breakerbar with a 5/8 socket located on the bolt of the pulley end of the tensioner,rotate the tensioner upward enough to release the tension on the belt,the tensioner is a spring loaded arm in a sense with a pulley on the end,if it will not move upward,try forcing it downward,if it wont break free you will need to cut the belt and replace the tensioner,let me know if you need more help.Thanks


ED