</font><font color="blue" class="small">( Looking for all of the experts opinion. Agco ST34@ is right at 60" wide, now I'm trying to decide if I should get a 60 or 72" rear finish mower. My 60" box blade covers my tracks perfectly, and I don't have to worry about catching it on anything since it doesnt stick out past the tractor. I will be using this to replace my dead lawn mower, so I need to get kinda close to some stuff, house, deck, barns, etc. Just wondered what you pro's have been using. Thanks. )</font>
To my mind, all of the above information is very incomplete.
You should not size your mower deck based on the width of your tractor, you should size it based on the available PTO Horsepower and your grass conditions.
If you are mowing thick lush grass and have a mower deck that is sticking out 6" wider on each side than your tractor's width, and you DON'T have the enough PTO HP then you really are just asking for all sorts of trouble.
Now I honestly have no clue what PTO HP you have so I won't recommend a width for you, but if you have very thick lush grass, you would probably want about 3.5-to-4 PTO HP for every 12" of mower deck. If you have thin or sparce grass, then you could use something closer to 3 PTO HP for every 12" of mower deck. This is for a FINISH MOWER, not for a ROTARY CUTTER.
Just my $0.02