I purchased a "Turn Key" remanufactured 6.5 diesel in 2013. It was supposed to be a back up engine for my fleet and was stored for 12 months before I installed it. When installed, it wouldn't run right. Injection pump had bad optical sensor. Replaced pump, my dime, ran OK but had noisy valve train, like a solid lifted cam. Called Eric, he questioned the timing of the engine, which was correct because I had done 20 of these in the last few years and I have the correct scan tool to do it, but he said it was "Normal". At 1200 miles, something let go internally, popping through intake sound. At first he wasn't going to warranty because I purchased the engine over the "12 months/unlimited miles" warranty. Finally they agreed to "go through it" but I had to pay freight back, another $750 on my dime. When I got the engine back, and installed, the valve train was noisier than the previous engine I sent back. There was also a excessive amount of blowby coming from the crankcase even after 500 miles. This replacement was a different engine because I previously noted the date on the block. I drove in hesitantly for 1000 miles and the noise in the valve train was a loud tapping now. I refused to trust these children to do a proper repair so I undertook diagnosis myself. I pressurized the cylinders to replace the valve springs and found 2 of the springs had broken internal damper springs and 2 of the springs had a different style internal damper spring, meaning it was not a matched set. What I also discovered when pressurizing the cylinders to change the valve springs was a massive air leak through cylinders 1 and 5. I reassembled it and put it back into service. The loud valve tapping was gone but the valve train was still very noisy. I know because I have factory low mile 6.5 diesels and the valve train should be silent. I ran it for about 6 months and it developed a coolant leak from the timing cover. They decided to use silicone to seal everything and the silicone seal failed after about 1500 miles. While removing the front of the engine to correctly seal the front of a 6.5 with gaskets, I decided to pull the heads to fix the leaking out of cylinder 1 and 5. Brought the heads to my machinist and discovered there were 2 cracks in 2 different exhaust seats, which wasn't the cause of the leak, and they "knurled" the valve guides to get them in closer tolerance to the valve stems. Now if I were in high school, and the was 25 years ago, I could see this as a possible repair, but now, replacement of the guides is the proper way to fix worn out valve guides with the available inexpensive tooling available. I called Eric and asked him if they surfaced the heads and he said "no they do not". A blatant lie because my machinist measured the pre-combustion cups and the were .010" thinner than original. The leaking cylinders were from poor valve seat contact area, like the stone used to cut the angles was worn out or broken. I junked the heads. Bought a set of new heads and installed. I runs better, valve train noise gone but there is still way to much blow-by for a new engine. Lesson learned. If new is available, spend the extra money and get it. The children at US Production Engines may be able to talk a good game but the reality is that they are a bunch of punks that don't understand proper machining techniques. Karma is a *** and it is coming for you Eric.