Weird, how is it when taking it off? does it require pry bar or anything? This is just how I always remember it. Maybe its not even half inch but like quarter its very small gap.

 

i (and told others who work on my car to) use RTV to avoid leaks ... i'm not sure if that adds to the effort required to remove the TC (i dont think so). I think the seal surface is dry at that point though so prying(screw driver) just give you some leverage. i just spread the old fluid on the seal surface before putting the TC back in. One time I needed to redo my install (forgot the small o-ring) it just came off and on easily

 

I always use alittle rtv to "glue" the o ring on so it doesn't fall off during install but never for the main seal. It could be the reason. Mine was pretty dry during install and could have caught while trying to slide in the last bit.

 

TRE puts marker/ink on the contact surface around the o-ring, he recommends the RTV there. I saw that he uses rtv on the axle seals and the large o-ring contact area so I do that too. I have zero leaks since I started doing the work myself