FF1538, that engine had a lot of problems blowing head gaskets back in 2007 and 2008, and I was told , when they sent out the replacement parts they sent out the same bad ones. The new gasket was just a single metal one. I have not had and problems with mine but it looks like a single one. Napa District manager came out to visit me at the end of last week, he took the filter back with him, and planned to send it back to Wix to have it tested. It will take a while to get the report back. In the mean time we pulled the pan off, and the #4 rod bearing had cooked and spun. it only turned a quarter turn on the spin. It did not damage the rod or the cap, but the babbit cooked right to the crank. We also pulled #1 rod and that had a small amount of scoring.. I have to pull the engine out of the machine now , and plan to pull the main bearing caps off next, The rest of the engine removal, should be easy. just the bolts on the flywheel housing are left, and a few wires and hoses. I have no clue how the main hydraulic pump is attached to the flywheel The parts book pictures are real poor. Right now if there are no more bearings spun, I might get off easy if i can clean all the crap off the crank. I still have to solve the problem of why did the filter gasket blow out? If they come back and say the filter is fine then I will have to do more disassembly to the engine. If the filter was deffective then I will just replace all the rod and main bearings , and I can do that without pulling the crank out, or taking the timming cover apart. Now as far as that books I have the skid steer operators manual. the parts book for the skid steers ht-30 thru ht-60aA, I have the perking engine book , but again it not a service type manual, just information about the normal maint requirements. The parts book that China just downloaded to me is incomplete, It shows most of the high use parts but not all . I would be very care full about the head gasket you put into the engine. Now this engine ownership has been drifting around for several years and it is used by CAT in a few of there machines, I also think CAT may even own the rights to it now. Your new head gasket will have the tourque sequence numbers wih it, but you have to be sure you get the right one . I think mitsubitshi has been out of it for several years. Perkins also has a main web sit that will assist you in obtaining the right parts. If you send me your email address I will download the PDF parts book to you if you like. china seems to have dropped out of the picture, but somtimes it takes several days to just get an email answered. I have been looking around for the engine service manual for the 800 series machines and I hav'nt found one yet. I might goto CAT next. Cat uses that engine in one of there popular fork lifts. I won't have any more info until I get the engine out and tipped upside down. I'll get back to you I saw all the torques specs for the engine somewhere, but again if they changed the gasket I'm sure the numbers would also change.