This may be a lot of blah blah blah to some but not forced reading. I've always wanted one of these digital tachometers so finally bought a $26 model at Harbor Freight. First thing I did was check it out on our 2009 RAV4 and also on my old 97 GMC. The digital reads in tenths but of course the auto tachs don't read that close. Anyway, as close as I could tell the digital tach was right on with the auto tachs. Now to the reason I actually bought it. The operation manual for my ym2002d states on specification page that my pto is 540rpm @ 2200rpm, 2nd range 1000 @ 2200 rpm, 3rd range appx engine speed. First off, my mechanical tach starts off being 37rpm fast at 700 rpm and ends up being 190rpm fast @2600 rpm. I guess a 30 year old tack deserves to be a little wrong. The big thing I found tho was 540 pto rpm @ 2360 rpm, 2nd range 756rpm @ 2360 rpm, 3rd range 1057 @ 2360 rpm. After having read thru some of these forums and other places I see other model Yanmars with speeds close to mine. I would like to think I could trust my owners manual but evidently not. My ym2002d is a vn polish job so it may be some of the pto gearing is not original. I'm more happy with the speeds I've discovered because I have been guilty of finish mowing in 2nd range @ 1800rpm on the mechanical tach which on the digital tach is only 1667 rpm which equals 540 pto rpm. Right on recommeded mower speed.