The notes from Mickey Mantle's emotional farewell address -- scribbled from his deathbed in 1995 -- is about to hit the auction block ... TMZ Sports has learned.

The speech is legendary ... televised from the Baylor University Medical Center on July 12, 1995 ... when a dying Mantle begged his fans, "Please don't do drugs and alcohol. God only gave us one body."

Now, we're told Grey Flannel Auctions will be opening up bidding on the handwritten notes for the speech that Mick had earlier scribbled on the back of a PGA tour score card in his hospital room.

One of the most memorable lines from the speech -- "I didn't know how Lou Gehrig could here [sic] at home plate knowing he was going to die and say he was the luckiest man on the face of Earth [sic]. Now I think I know."

GFA tells us the item will hit the auction block at the end of April. There will not be a starting bid.

Mick died just 4 weeks after the speech after suffering from liver cancer, cirrhosis and hepatitis.

He was 63.

