Gear Box ( Walker ) ?

What would you do? I have a Walker MT-54 and the main gear box the shaft that the PTO goes into has a crack near the key-way. Would you just replace that one or would you replace all 4 of them on the deck? Mower has approx. 650 hrs. on it. Thanks for your advice.
Mowman

 

i would just change that one , good time to open and inspect
the others,change the fluid and check for metal filings then make a better dission about changing the rest,how did you manage to crack that shaft i had a hard enough time cutting the pto shaft off that thing is soild steel, what did you hit?of what was out of balance?

 

I bought this mower used. I'm sure the previous owner could tell me what happened. I have hit nothing. It was leaking fluid so I replaced the seal, this is when I discovered it was cracked at the keyway. He must have hit something very hard. Thanks for your input.
Mowman