That may be true generally but it is not true for my 300SD. I have personally tested it when I replaced the tranny. It goes to zero vac as soon as you hit the throttle and gives very smooth upshifts. I doubt if you could drive as fast at 10MPH and still have any vac distributed to the trans modulator on mine.


It clunked badly however on downshifts. When I pumped up the Mityvac, the downshifts were perfect. If there is some difference with very show coasting downshifts, I did not notice it at all.