I have an 86 1/2 ton with a rebuilt c code, banks sidewinder kit and timing gears. I also have a set of J code heads kickin around. I am wondering what the difference (if any) is in with the heads (valve size?). Also in anyones experience is this a worthwile swap considering my trucks already turbo'd? Local machine shop says about $280 for both heads to clean, magnaflux, check valves/seats and re-seal them.

Thanks for any input.

Only difference should be the C codes have an EGR passage..... and that wouldn't make any difference without the J code intake at the same time.......

use the money on the heads to have them shot peened and treated to resist heat better... ive seen alot of 6.5s down here in south florida with cracked heads...

id have them CCed at the same time too...

Since we don't make a whole lot of HP with these motors just stick with heads that are not known to be crack whores.
My 162 heads are considered "small valve" but they are not known for cracking.
Some of those big valve heads are known for cracking.