i have a vortec block with patriot heads and i am putting sepertine accessories on it that came off of a 94 2500... of the brackets i have only the left side will bolt up and the right is off by about 3/4 of an inch... i was wondering if G.M. ever changed the pattern on the brackets they used if so which brackets do i need to cheaply get back running again  

patriot heads are manufactured by pro comp=chinees produced not as accurate
you didnt mention which bolt holes dont line up the head or block???  

In '96 when GM changed the trucks over to the Vortec heads, injection system, and started putting hydraulic rollers in all the motors, I wouldn't be surprised if they changed something with the accessory drive system.

Even for Chinese production "tolerances", 3/4" difference is a bit much. What kind of car are you putting this motor in?  

86 K10 and it is only one hole in the head that dosent line up... i figured it out though, the heads are machined for 86 and earlier style accessories... so i got the bolt in the head and the bolt in the block that line up and used the braces that came with the donor engine; problem solved

Thanks for the help