That sounds like a nice one. The problem with used diesels is most are used by landscapers and have had a hard life. Gas models are more common for homeowners, and like the one you found some are really cared for.
I know I gave you a link to the GH site for a manual, but here's a link to a valuable resource:
Grasshopper Lawnmower Parts - Grasshopper Mower Parts Diagrams - The Mower Shop, Inc. You can look up parts and find current prices for comparison or to use the numbers for web searches. I use that site quite a bit.