Honestly, you got me thinking! I know the guys that built the rig this was out of and when they called me I asked the same question. But now you have me wondering the same thing. I need to check with them to see if they actually put a custom shaft in the case. I'm guessing not, but I want to confirm so I can update ad. I've had it quite a while thinking I would use it behind another 700r4, but did not think about tha Advance Adapters shaft for the trans. I rarely ever mess with the lighter duty stuff, and appreciate you bringing that to my attention.