I know the they were offered on 280 Sl's in Europe until they went out of production (1985?) because their shown in some of the original English sales brochures I have. I figured they were offered on all of the models sold in Europe. I know it was first introduced on th 500SL and that model probably had them exclusivly during the '70s. What model 500 do you have? I have a line on a 77 with a 4 speed the owner might want to sell cheap.