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Message: [QUOTE="Gearhead2012, post: 913742, member: 12934"] The 6.4 valve train components are all that's available from Ford. The 6.4 pushrods are 9.800" while 6.0 pushrods are 9.850. There are technical service bulletins about why they now recommend a .050" shorter pushrod, but in a nut shell 6.0's have waaay too much hydrualic lifter preload from thr factory which leads to the occasional misfire when the lifter actually forces the valve open at the wrong time due to the oil pressure in the lifter. I would recommend going with the shorter pushrods whenever the motor is apart, theyre cheap, and it lessens the lifter preload by .050", putting it closer to where it should be. The lifter plunger has around . 200" travel in the body, ford specs that you should have about .035-.045" lifter preload, but most 'virgin' 6.0's have about .150" preload.... Waaay too much. We set the valve height about . 030" lower than stock and use the shorter pushrods to achieve the adequate lifter preload of about . 040". As for the rockers, if your stock ones aren't worn out, keep them. The 6.4 rockers have an oiling hole in the pivot (the part that rides on the bridge). The goal was to allow more oiling to the upper engine valve train components... But in actuality it just bleeds off what little amount of oil makes it to the pivot anyway. Plus, the 6.0 rockers have a chrome plated pivot, which holds up better than the hardened pivot in the 6.4's. The 6.4 pivot wears out quickly and then begins to bind up on the bridge and cause excessive valve guide wear. Despite 6.4's newer platform, and theoretical lower mileage over 6.0's, we throw out waaaay more 6.4 rockers than 6.0's, and I replace waaaay more 6.4 valve guides than 6.0's. Lots of factors there, but the change in valve train components from the factory is a big one. I'd change the pushrods just for the lesser lifter preload, but leave the rockers alone of they're not worn out and sloppy. [/QUOTE]