1995 jimmy leakes out antifreeze back by the tansmission what could this be?

It could possibly be that your heater core is seepng coolant and it is going out of the A/C system drain hole which can be near the area of the transmission. Do your windows ever get foggy when you turn on the defroster?

I had the same problem , I had to replace the Intake and Valve cover gaskets. From what I have read and seen online ETC its a common problem. Mine leaked at the front of the motor and ran back down the rear of motor over tranny