I think the way you read it is its a 9-22 651

Made 1989 (9), its 22inch (22) and 651 is the model


If what they say here is correct, then it would make sense it is an 89 as its the last of that model designation system

https://www.mytractorforum.com/threads/murray-model-numbers-and-doms-explained.145127/

Its in good condition for a 32 year old mower