I have just completed a change from manual to auto on a 1970 280sl,had a 71 108 as donor fitted cooler in radiator lower tank,cooler pipes,flywheel,shortened front of driveshaft and rebalanced,removed pedal box then fitted shorter bolt for brake pedal mount,fitted 108 speedo cable,vacuum pipe,kickdown switch.Interrupted wire to starter solenoid and put back via inhibitor switch,also included wires for reverse lamps.The auto box is the k4c025 type so did not have to add idle switch on throttle body or constant speed solenoid.Biggest challenge is shifter rod,connecting early type shifter ( back to front shift pattern)to later type auto.inverted lever on side of auto and made up linkage in between.I have pattern of correct shape and ratio,cut and bound carpet of centre console.About four days work,now everything works and drives perfectly.