Fragile? Two years ago I sold an '88 and a '92. Last I heard the 92 was still being used commercially. New owner put a short block in it (Kohler 16). These mowers survived an employee we dubbed "cowboy carl" on his first day because of all the stuff he hit. He's a great guy, but I finally had to let him go. I thought he would be a better operator with practice.
I still use a 3 blade 54 inch deck daily in the mowing season. It still has the original gearboxes and shafts, bearings & seals have been replaced. Deck has been out of production for years. I think I bought it in '90, 23 years ago.