when I bought my 81 SD I took it to a lube shop and they disconnect the lines at the radiator hook them up to a big machine and back flush the whole tranny and torque converter they don't drop the pan and claim that the flushing cleans the filter . You can see the dirty fluid coming out and when it's clean and full they disconnect the machine and hook the radiator lines back up. Fluid is sparkling clean after 6000 miles cost 80 buck ? No do have to lie under car with fluid dripping in hair or worry about leaking pan gasket (I do all other maintainence myself)even suspension work but hate filter change on tranny.....
William Rogers....