Haha, I wasnt sure if anyone was even reading it...sorry for th elate reply last week was crazy busy as we had a snowstorm blow through. Unfortunately the 743 was still apart so had to rent a very nice 2 speed kubota with an enclosed cab...after the rental bill on that though, im looking forward to having my own machine doing the work although it will take a lot longer. So anyway, I found out that the "metal chain guides" I was reffering too have been since replaced by some plastic ones. In the parts catalog they reference them . It makes sense because the metal ones clearly weren't working. So I ordered timken bearings, national seals, bobcat wear rings, the new style chain guides off ebay, a seat, a couple tilt cylinder pins, etc. All is here now, and ready for installation. Im planning on using my old sprockets and chains maybe puting a half link in or something. My chains have an 1/8" stretch over two feet so doesent seem too bad to me but hopefully someone has some better insight. My two hardlines that run along the floor behind the blowerhousing were definitely not looking good, but i capped an and and applied compressed air, but failed to find a leak. Got my hydraulics shop to chop the 12" off them that was corroded, and add in a new piece so i should be good for another 40 years! However I am now really trying to find out where the oil is coming from...rearmain on the motor looks good, im pretty sure the hardlines were fine, the seal on the gearpump doesent look bad so perhalps the oil cooler but i pressurized it with compressed air and got nothing either. It has oil stuck all over it and so does the blower fins so oil is coming out of somewhere and the blower is just whipping it everywhere. Checked the glowplugs and they seem fine, replaced the v belt so the motor is ready to go back in. Could do an oil change now but id prefer to have the oil warmed up for a better drain out. So to directly answer your question, No I dont know the specific year, but based on having the bronze filter in the port block, along with the old style chain guides I would conclude it was from the first 5 years of production. 1980 - 1985?