I have access to the CSUs from 87-88 to 95-96. Gravely never did produce the lists for the 4-wheeler serial numbers ofter than what you see in the 88-89 CSU. To make matters worse, from 1982 to 1992 Ariens/Gravely used two sets of model numbers. The crossover sheets for them totals over 1500 PDF pages. And it isn't even complete.I'd be willing to review. The PDF link from your referenced thread, I had not seen before and it is pretty good. I still have yet to find a definitive serial number chart for the riders like I've seen over on stevenchalmers for the 2-wheelers. Wonder if such a thing exists or is the engine manufacturer maybe a better source in general as far as pinning down a year.
We should take a stab at answering the poster's question though I think. Maybe he can be a little more specific as to what he's after...shopping for a first machine, etc.