His is a newer jeep I believe it has the 4 speed automatic.
Well, if he wants to get it back on the road fast and cheap he should stick with what it has. Otherwise, swap away. A 32RH/TF999 would be pretty bullitproof but he's lose OD. AW4 is an option as well. If he wants to do adapters then a TH700R4 or a 4L60E would be a good choice. They're super common unlike the AW4 but adapters aren't cheap.