Are there some on the back of the engine? How can you tell if they are leaking? Would you have to remove the engine or transmission to get @ them to do the below?
If you have identified a leaky freeze plug, you can: (1) drain the system, (2) clean the depression in the freeze plug with Scotch-brite and a cleaner like Simple Green to remove both grease and water- soluble deposits, (3) after it dries, apply a liberal amount of putty type steel filled epoxy to the inside of the freeze plug. If you aren't familiar, they are shaped like shallow flat-bottomed cups with an inside diameter about the size of a quarter. What you want to do is to cover the hole with the epoxy from the bottom of the cup up all the sides to the rim, where there is no corrosion