Any 4.0 or 4.6 block regardless of inlet or management system can crack. Even the 3.9 blocks can do this. Any block with a 94mm bore.

The 4.0 motors seem to have the most problems closely follwed by the 4.6 motors.

There are a few theories as to why this happens. Some believe the high engine running temps of the later management systems are to blame, some believe the high stresses involved with the angular torqued head bolts are to blame and some say they're just plane rubbish and will crack no matter what. No matter what the reason though they can all suffer from it so its something that needs to be checked or you could end up paying out more to get things repaired or replaced.

If you're checking an engine thats out of a car and in bits try to get a look at the pistons. If any of them look very clean when compared to the rest which would in theory be black (if the engines covered some miles) then run away. I believe its the rear cylinders that are most prone to this however i'm not sure on that but it could happen to any cylinder i suppose. If the engines running in a car look for head gasket type symptoms .

There are different grades of block though. They are graded on the thickness of the alloy of the block behind the liners. The grade is a colour, one of three i believe but i don't know what they are or where the colour marking is on the block. This could be worth looking into to get an idea of the blocks quality.

Hope this helps!

Grüße und happy rovering
Stephan