Front Diff leaking oil, seal confusion

My front diff has been leaking oil on the drivers side, right where the CV joint enters the diff. There is a bit of play between the CV joint and the diff... not sure if this is supposed to be lose? anyway, I have a second hand part and in the middle of the switch I figured I should just change the seal and see if that solves the problem before I put the newer diff in. the seal was clearly damaged and I picked up a new one from the dealer... but its very different and the parts guy said they have changed the seal design?

1. should there be play between the left CV joint and the front diff?

2. How do you go about changing the diff to accept this new seal?

Thanks

and a tip for all those like me who are just entering the world of "fixing your own truck": have another vehicle around... because as soon as you pull your wheels off you find out about all those things you need to pick up all over the city! arrg

 

Figured it out, you just pull the old metal ring out then put the new seal in.

 

Good to know.

 

That's Toyota Part # 9031147012. I was just looking for it. The pic helped a lot so I added a little more.