My number is 626500684 (600 units after yours). My machine is a 1993 which was the first production year for that model, so I think that answers your question.
This little machine has done everything I've asked of it. It fits easily in the woods and is a real workhorse in the field. Would I like bigger? of course, but it seems to be the perfect machine for going up & dressing the logging trails, mowing the fields, moving tons of materials, back-filling & leveling ditches, etc, etc. In a nutshell, a great old school, basic non-sexy tractor.