95 sierra tow capacity

Hey guys...the tranny in my car took a shit so im needing to tow it...I own a 95 GMC sierra Ext cab....its a 1/2 ton 2wd...Ive used it to tow many cars with tow straps....now im gonna have to trailer the car since it is about 120 miles to where it needs to be.....According to uhual my truck isnt sufficient enough to tow my car on the trailer.......Is that cause my truck cant hanlde it or for other reasons?....I dont have a hitch either, just the ball on the back of the bumper......anyone here think it can hanlde it or should get a bigger truck?

Thanks