I also agree that the '76 and earlier 450s should be avoided. The '75 and earlier cars had the electronic injection which was troublesome and, as mentioned, the '76 had the catalyst under the hood. Best bet would be a '77. '78 and later are equipped with climate control which also can pose headaches. We've owned our '77 450SL since new and right now it's reading 169K on the clock and has yet to ever need any major work. Unfortunately I haven't driven it since last May, I just don't have time anymore to get my "fun" cars out. I keep them in a climate controlled garage and since the 450 rarely gets used, it is on jackstands and is covered up. Hopefully this summer I'll find time to get it out for some exercise.