The D within the engine code means twin overhead camshaft (DOHC). That is attained by fitting an RB25DE or RB26DETT cylinder head and or turbo to a typical RB30E/T block. The RB25DET is not really generally used. The RB25 crank collar difficulty is definitely very common on various RB motors, https://caidentvool.blogmazing.com/27858592/not-known-facts-about-new-rb26dett-for-sale