I have to admit that I never noticed the difference in my paperwork regarding the horsepower. My 523Dxi is also a 1998 with serial number 890556 with the DM950D engine. The Groundsmaster mowers actually switched to a Kubota diesel but kept the Daihatsu gas version later on. Then there is Toro also using the same engine in their Groundsmaster mowers and Workman Utility so that could also factor on the switch. Keeping a 23 horsepower rating may have been under the requirement. I seem to recall that ROPS began to be required around this time period. Another reason could be a change in regulations, here or in Europe, regarding horsepower. Regarding the switch, it could be that the DM850D was less stressed for the application with less cubic inches and/or cheaper so it began to be substituted. The 523Dxi was originally developed for the European market and then also sold here in the USA.
