[Tacosteelersman]

Congrats on the 1641 and time with your grandson
Grease fittings, one of my favorite things. There are 3 on the front axel alone, I get confused sometimes cause I have several machines I maintain. As Sam said drive shaft and steering gear. There might b one on the deck mule drive. The deck has lots of em remove the belt shield. Should be a fitting on every spindle, every wheel, and front caster pivots, also check the tensioner pullys for after market zerks. Also check your front wheels for wheel bearing zerks.
Things without zerks I use spray grease on moving parts, my favorite is Castles muscle grease. Just keep that stuff off your belts and pully grooves, it will make them prone to slippage.