What to look for? Is there anything to check while it's out of the truck without cracking the case open?

I'm trying to buy my buddy's cherokee to use as a DD/ Plow Truck. I drove it last year(we put a good 80-100 hours of hard plowing on it, plus it had been used by a guy for personal plowing since it was new) and the 242 finally let loose. He spent 750 to replace it, but I see them selling for 100-150 all the time.

So I'm assuming the worst will happen this season, and want to have a 242 on back up just in case.

Is there a way to check for slack in the chain? Anywhere to look for cracks or damage?

Thanks.