How do you change freeze plugs on a 2.8L motor in a 86 firebird and due you have to take out the motor and transmission?

They can usually be pried out with a screwdriver and knocked back in. Most can be got to with the motor in place somehow. The 2 in the back of the block require either the motor or trans. to be pulled. For me, pulling the motor requires less effort. Less wiring and plumbing.