Oh it was definitely a trans leak....and fluid was too high at op temp at idle, in park. Fluid had run down the housing to the pan, then, apparently, the high-speed cruising sent the fluid on a nice journey back down the cat, to the muffler....ah smoke. Shall drive it gingerly for a few days to make sure all is well. Seems to shift better now.....not as harsh.......which would indicate high fluid. Guess the overflow valve did its job

__________________
former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL