I have never rebuilt a carb in my life, however I don't see it being that difficult. Any pointers on rebuilding one on a 48 Cub? Are there any special tools required? Also, I may not need to do a total rebuild, was told that the main jet maybe clogged; can it be cleaned without removing the carb from tractor?

There's a first time for everything, right? First one I did I messed up but mostly because I did not understand the concept of packing around the throttle and choke shafts and installed it wrong. Just did an IH carb off a 1957 Loboy last week and it was the fussiest of all only because of it's size. I think you can handle it. A word to the wise, though, (in my best Shakespearean voice)...beware the idle tube. It is threaded shallowly into the top half and fits down in a hole in the bottom. On the IH carbs (can't vouch for Zenith) you need to seperate those halves straight up or you will snap it off in the threaded hole and you WILL be getting a tiny reversing drill and probably a tiny tap to chase the threads. Mine was busted off when I got it and the bottom half removed. I hear this happens a lot. Otherwise, to make my point, if you have a clogged main jet I would at a minimum disassemble the whole thing and soak it and blow out all the ports. You may not need a rebuild kit but if the main is clogged I would have to think the idle circuit is likely going to come back and haunt you if you don't address it now. Clean the outside of the carb well before disassembly and soaking. Just an opinion.

Thanks.

NO 1 BUY AN IH CARB KIT
do not buy a Tisco kit or any other brand
even if the IH dealer sayas it will work, is just as good, etc
NO 2 BEWARE THE IDLE TUBE
no 3 straighten the top carb body
all of this and more covered in farmallcub.com how to do's
I prefer the article by Lurker Carl
also look at the list of Cub gatherings, try to attend one
GOOD LUCK
Ron

I.H carb kit only , it may cost more but the end result is what you want .

Find a manual, book or instruction sheet with step by step instructions, diagrams, part number and settings.specifications. Or a friend who has done a dozen or so.
Doing your first carb "blind" would be a disaster.