The DD 8.2s are in fact diesels, and have the unit injector system that Detroits are known for, but they're 4 strokes.

They were also called "fuel pinchers", although they were never really all that good at extracting the higher-BSFC numbers we now get from electronics.

They're parent-bore engines and have an "open" block deck design, which means that they're prone to head gasket problems. Early year engines also had too small head bolts for proper sealing pressures.

The 6.5 is a totally different motor.