RODNEY - An old original manual is better than NO manual, but any time you have something as complex as a parts manual for many different models of tractors with ALL the possible variations of attachments, MISTAKES will creep into the manual.
Having dealt with Harvester Press years ago getting owner's manuals & parts books for FARMALL, I also got later versions of parts books frequently. Think I could get 2-3 per MONTH just by calling and asking for them if they were in stock. I could BUY anything I wanted and also went that route several times for my growing fleet of IH equipment, getting parts & service manuals.
Right in the very front of the newer reprints of parts books were MANY pages of "CORRECTIONS" stating page, item listed, and the correction. I always updated the incorrect items in all my new parts books so I didn't have to check the correction pages.
But with the parts look-up above showing all the new MTD part numbers when you actually go to a dealer or talk to Charlie or one of our other sponsors about parts you should always try to use the latest part number available. LOTS and lots of parts have unfortunately been deemed NLA but alternatives are available. I'd say parts are easier to get NOW than they were 20 yrs ago.