Ok, basically I got screwed out of an GSR transmission & its an LS with a broken Diff. I already have a GSR diff i'm trying to throw in there. I bought a ITR final drive kit (4.40) to swap the GSR diff in there to temporarily use this transmission. My engine builder is saying the ring gear will not fit onto the both of the GSR diff's I have. (one oem, other obx LSD). I'm thinking I got screwed again & since it is a 4.40 it must be a B16 ring gear. My question is, does someone absolutely know that an ITR final drive fits & is a direct swap over to a GSR. It was to my understanding that the GSR & ITR we're completely interchangable like the B16/LS are. I really need to be sure before I take any course of action with this guy through ebay. PLEASE SOMEONE HELP!