I have a LQ4 6.0 with 260,000 miles on it and I would like to replace the valve springs and seals. I have talk to the tech guys at SDPC about a set they sell, here is the webpage, they said I could have a lifter problem due to the high mileage. I forgot to ask about the LS6 springs. I would like to go with the LS6 springs but I am not for sure if they will fit, are they 1.800" installed or 1.750" installed.

 

I believe they will be a direct replacement for any lsx based head.