Another noob with Clark forklift questions

Hi-
First time poster here. I "inherited" an older Clark forklift, and I was wondering if anyone could help me decipher things like model year, etc. from the data plate?

It's a Clark C500Y180D with sideshift. Any idea what the "Y" and "D" in the model number indicate?

Serial number is Y1625-09-5570CB. It's rated for 18,000 lbs. I found and printed an Operator's Manual for the C500 Y 180 (and larger units), but while this manual gives info on LPG, CNG, gas and diesel-powered...

Another noob with Clark forklift questions

Another noob with Clark forklift questions