A quick way to tell: look at the shifter housing. If it is parallel to the tail shaft then it’s a 71c (commonly known as rb20 trans, but found on RB25DE). If the shifter housing slopes back toward the ground then it’s an RB25DET trans. Side by side the difference in size is obvious, in photos alone not so much.
you could swap your RB bell housing onto a 240sx 5 speed from a KA car and it’ll move the shifter back.