I have a 99 GMC Sierra with a 5.3 and I blew the motor but the heads are still good and the casting number on the heads is 862 I got a really good deal on a 5.3 out of a 2005 Chevy Silverado but 1 head is messed up cause of faulty friend . I . the casting number is 706 I need to know if I can swap it or will there be more to it.

 

Yes, they'll swap over. They're almost identical cylinder heads.

One thing to look out for is a "void" in the deck, for lack of a better term. It requires a specific gasket if you do have it that GM and even Fel Pro makes. Some 862 heads have them and some don't. I think all the 706 heads have them though.

 

KCS is pointing you down the right road.

The felpro permatorque gaskets have a relief cut into them to accommodate that notch. You can get them in a variety of thicknesses also.

The cometics will leak if you try them

The composite gaskets will work - again as long as that relief is cut into them