Hi Tim
If she has 4WD and a Perkins engine she will be post 1980 afair. (JCB 3CX model)Perkins 4236 engine.

Earlier than this were only 2WD (model 3C) and had a BMC engine with wet liners which had a habit of dropping, the Perkins was a huge improvement.

Some MF tractors will have the same or very similar engine.

Would he not consider a rebuild? Not so expensive I would think although a while since I did one.

Link might be useful

.https://en.wikipedia.org/wiki/Perkins_4.236



Jim.