Remove & Replace Catalytic Converters in 04 VY Exec series 2. Help Please!

[S-Man]

Hey Guys, Newbie here and I need as much help as I can get if you would be so kind!

My cat converters need replacing. I havent an idea where to start and what equipment I'll need.
Can anyone tell me what I will need? Do I need to replace 02 sensors or just clean them?
What size cats should I get? 2 1/4' or 2 1/5' or 3'. Do I need new gaskets/seals?
What tools will I need? Where do I start?

I appreciate all your hints and tips

 

[Big-Al]

take it to an exhaust shop. it'll work out cheaper in the long run.