Tubes, Slot Hitch, and Belt Guard ?'s

[jellyghost 378]

I want to get my Suburban 550 in running shape and I have a few questions.

 

Tubes:  I heard people talking about putting tubes in their leaky tires.  Is there any problems with this fix?  Should I just order new tires?  Where do you order tubes for a tractor like mine?

 

Slot Hitch and Plow:  I bought a David Bradley plow/disc at an estate sale today.  It is really heavy, but it looks like it should slip into the 550's slot hitch.  I am hesitating because it doesn't seem possible that the little 550 is designed to raise and lower so much weight.  Am I underestimating the tractor?

 

Belt Guards:  Who makes belt guards for this tractor?  

 

Thanks in advance!