I am halfway through mine right now (1983 300SD). I followed instructions I received on this forum as follows:
1) remove pan and drain
2) remove 4 bolts on back support and lower trans about 2 inches
3) pust B2 in with a prybar and remove retention clip
4) My B2 came out in two pieces along with the spring and a 2 or 3 inch bar.

I ordered the part and it should be here on Monday.
My question - Where does the bar go when I put it back in?