Head Gasket change?
 

How hard exactly on a 99 SR5 4x4 to change the head gaskets

I've had a '94 3.0 V6 apart down to the heads, and the toughest part was all the junk on the passenger side of the intake--keeping those hoses straight, and being able to reach them for re-installation was the hardest part. I don't know if the '99 is the same set-up, though. As for the heads, make sure you check for absolute level on the surfaces before reassembly--if they warped, you'll need to have them machined back to true, or the gasket will just blow again. Good luck!