The D from the engine code stands for twin overhead camshaft (DOHC). This is often accomplished by fitting an RB25DE or RB26DETT cylinder head and or turbo to a normal RB30E/T block. The RB25DET isn't commonly used. is a sturdy engine, powering more than 3 generations in the Skyline GT-R. https://nissan-rb26dett-engines-f72578.fireblogz.com/59544988/top-latest-five-nissan-skyline-rb26-engine-for-sale-urban-news