12) Your cats and Y pipe are now all installed, but not tight. Start with your cats...rotate them so the O2s will screw in. On the driver side you'll see if you don't rotate the cats correctly your 02 sensor will be touching or very close to the front transfer case drive shaft. So plug that O2 sensor in, rotate your cat for the perfect position, then cinch up the cat to header connection. Obviously you want to tighten these three bolts evenly. Same thing on the other side. Make sure O2 sensor positioning is good to go and cinch the cat to header. You'll remove the O2 sensors after test fitting them, so you can get to the top bolt of the connection at the header/cat.
13) Now you'll have two sleeves mid Y pipe, and the connections at the muffler. Tighten both pipes at the muffler up, making sure your sleeve connections are nice and lined up first. This will allow for very easy final adjustments when you tighten the sleeves up.
You'll use the old bolts at the muffler end, so don't toss them when you take the old system out. FYI- I used a map gas torch to get the old connections loose at the muffler. Those were on good and rusted. The heat helped make it happen.
14) Now you have two more connection points mid way between the cats and muffler. One is on the cross over from driver to passenger side pipe, and the other is just after the passenger side cat. These connections are male/female so sliding the pipe in and out to the perfect line up is a piece of cake. Make your adjustments if needed, and tighten the sleeve bolts up. You might want to grab your tranny brush guard and make sure it fits, IE your exhaust is not hanging down to low. It shouldn't be an issue if you've lined everything up nicely.
These two pics show different angles of the O2 situation on the driver side
Y-pipe crossover sleeve. The sleeve on the passenger side is hidden by the crossmember