The t-case will have a 21 spline input when it came with a 2.5l manual transmission, one off a 4.0l won't fit, it's 23 splines. Also, one off a 2.5l with an automatic will have 23 splines.

Repairing the front drivehaft will probably be the cheapest by replacing it with one from a wrecking yard. If he's lucky, he will find one in a pick-your-part type yard. He might be able to get the fuel & brake lines and wire harness, too.

Usually I would see such failures after the Jeep (YJ or TJ) hit an obstacle on the left front side, the axle control arm bracket/s (TJ) or spring (YJ) would bend allowing the front axle to come back enough to jam the driveshaft and crack the case off the transmission in the exact same manner as what happened to the one in the pics. The front driveshaft front yoke will be missing the plug for the splines, the shaft will usually be bent, too. The chain in that case is not broken. Usually they only will break/snap if the case were out of oil. If this is what happened, the front axle tube/s may be bent, the lower control arm brackets are available from Currie, if the tubes are still straight.

If it was an accident that caused it, they may wish to check their insurance, it may cover the damage.