There are some minor differences between 4D56; Cylinder heads, valves and pistons are different between 4D56 manufactured before and after 1998, but the change also depends on the vehicle.

I know that the Hyundai D4BF is identical to 4D56T prior to 1998, the Hyundai D4BH is identical to the 4D56TDI present on the post-1998 L200 truck.

Almost everything is identical and interchangeable on Hyundai D4BF/H and Mitsubishi 4D56, except for some accessories like alternator and alternator belt.

Also, there are some variation on the turbos. Some models are water and oil cooled, some others are only oil-cooled. Most old 4D56 I've seen are oil-cooled only. Most D4BH and later 4D56 I've seen are water and oil cooled. Also, some newer 4D56 engines have variable geometry turbos and electronic fuel pump, producing 115HP instead of 100-105HP.

I would say build quality on the D4BF/H is a non-issue.