"New" Transmission Still Flaring From 3rd to 4th

This is continued from "air bubbles in transmission fluid" (http://www.peachparts.com/ubb/Forum1/HTML/004428.html):

I picked up my 84 300SD today, which (supposedly) just had a new transmission installed. So I checked the fluid about 20 miles down the road, and it was about an inch above where it's supposed to be (still with bubbles in it). So I turned around to head back to the shop that worked on it. And once it's good and warm it starts flaring from 3rd to 4th gear under medium acceleration, exactly like it was doing before the new transmission was installed. They think it's a vacuum problem.

Is there any way I can tell if they really put a new transmission in there? Is vacuum problem a reasonable diagnosis?

I'm obviously not going back to this place after this, since they can't even get the FLUID LEVEL right! And I'd be happy to tell anybody who they are.

Can someone recommend a good independent Mercedes shop near Santa Barbara?

Thank you for your help.

------------------
Dean
Santa Barbara, CA
ICQ #300030
1974 280C
1984 300SD