The D while in the engine code means twin overhead camshaft (DOHC). This is certainly accomplished by fitting an RB25DE or RB26DETT cylinder head and or turbo to a regular RB30E/T block. The RB25DET is not typically used. Still, the two are rather equivalent, as well as RB25 is actually https://manuelfuysr.blogcudinti.com/28190053/nissan-rb26-engine-an-overview