When I was shopping around for a used compact tractor I came upon some brands and models that I was not familliar with.   I had never heard of Yanmar tractors, but I found a handful of them at very reasonable prices scattered around the area.  After searching online I found that Yanmar had manufactered compact tractors for John Deere for several year models during the 1980s.  In fact after looking thoroughly at my fathers compact John Deere (15hp), I found the Yanmar manufaturer ID plates on the diesel engine.  My father has used his John Deere for many years and found it to be extremelly reliable.  This information  and the low price  was enough to make it an easy decision to buy the Yanmar YM-1300d I had been looking at.  This is a 13hp 4wd compact diesel tractor.    I have used this tractor for about 5 years now and have been very pleased with it.  In the first few weeks after I bought it, I spent some time online searching for user and service manuals.  During this research I learned an interesting fact.  I had purchased a "Grey Market"  tractor.   
I had never heard the term before, but I was able to find some good information online.    A "Grey Market" tractor is a used tractor imported from another country (usually Japan) which was not specifically manufactured for sale in the USA.  Many of the grey market models match nearly identical  models which were manufactured specifically for sale in the US.  The main differences lie in some of the safety features .....

of the tractors.  All tractors manufactured for US sale with a stick type throttle must increase engine rpms as the stick is pushed away from the driver and decrease rpms as the stick is pulled back towards the driver.  This is reversed on Japanese made grey market tractors.  It is easy to see why this is a stractor throttleafety concern.  A person who drives tractors often, would probably habitually be inclined to pull back the throttle to stop the tractor.  If they happened to be driving a grey market tractor, this could be disasterous as it would cause the tractor to speed up instead.  Another safety concern is the lack of a pto overun device.  The Japanese do not use many heavy rotary implements like bush hogs and other rotary implements, and therefore have little need for an overun clutch.  Without this device the inertia from the rotating blades on a bush hog can be  transfered to the drive train of the tractor even if the tractor motor is stopped.  This became a real danger for me the first time I came to the corner of my fence while mowing with a 4 foot bush hog.  I pressed the clutch in an attempt to stop so that I might back up into the corner to mow closer to the fence.  Although the clutch was released the tractor kept lurching forward driven by the heavy rotating blades of the mower.  Luckily I was able to jam the brakes and quickly jerk the transmission out of gear before I smashed through the fence.  There is another difference with the PTO.  Some grey market tractors have multi speed PTOs.  Most compact tractor models matractor PTOde for US sales have a sigle speed PTO.  This sounds like an advantage for the grey market tractors and I believe it is, but be aware that most implement made for compact tractors are made to run at RPM speeds standard for US small tractors which is equal to the lowest setting on most grey market models I am familiar with.   This means that if you run a mower behind a tractor with the PTO in third gear, it could vibrate to pieces in a short time from the increased RPMs.  I ran my bush hog with the PTO in third gear ONCE shortly after I got it.  It sounded like the mower was a few seconds away from lift-off and I quickly hit the clutch.  These are small differences that do pose real safety threats when users are not properly informed.  It is very important to keep these differences in mind when you purchase and own one of these grey market tractors.
Given these differences, drawbacks and advantages, and considering my personal experience with my Yanmar 1300d, I do believe that these tractors are a good value for a yardstead.  It is very important to understand the differences and safety concerns and keep them in mind as you operate your tractor.  If you plan on using a grey market tractor for mowing, then I would highly recommend adding a PTO overun kit.  These are available from many sources online, along with much more info such as manuals and cross references to US models.  I have not added an overun kit to mine yet, because I rarely use it to mow.  I use it mostly for tilling with the Yanmar tiller that it came with, which does not cause PTO overun.  This tiller can also take advantage of the faster gears on the PTO as well.  I may add one in the future though, as time constraints may require me to use it for mowing more.  This will be covered in future articles along with much more details about compact tractors.