T shot is not a duplex load like salukipiv1 is saying...T shot is a .20 size pellet.

if the law reads like you say it does, i would go with copper platted BB size loads. they are size .18. for yotes, i know most guys like #4 buckshot but that is larger than you are allowed. most T shot is steel or waterfowl loads...

http://www.hunter-ed.com/id/course/ch2_shotgun_ammo.htm

hevishot does make a "dead coyote" load, and it is size T...heavier than lead...and supposed to be awesome stuff, though expensive..dont know what your law says about using hevishot...
http://www.hevishot.com/products_dead_coyote.html

id definently stay away from #4 turkey loads..i shot a red fox at 20yds..drilled it in the head with a copper plated load of #4 turkey load...it rolled and died instantly, but when i skinned it, i noticed a heck of alot of pellets didnt penetrate the skull. i got the head in the back yard to see how much damage it really did...but i wouldnt use it on a yote...

copper plated BB size loads, or the dead coyote loads would be my choice in your shoes...make sure you pattern with whatever your decide on...find your max range and stick within it...