VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 Chatter from trans or clutch?

I have a 47 Stylemaster that is giving me lots of chatter in first gear when taking off but smooth in the other gears when the clutch is depressed. I understand the need for new motor and transmission mounts with the proper alignment from the manual.
I looked that up and don't understand this portion:
3. Check the clearance between the transmission cross member and the "U" section plate (pas­senger models only). This clearance should he from .005" to .015", equally spaced fore and aft. If the clearance exceeds these limits, remove the mounting and bend the "U" section plate until the clearance is within the above limits.
What is the "U" section plate they are talking about? Pic would have helped me...visual guy!
Thanks for your time and advice.

The inverted U shaped plate sits over the top of the rubber of the transmission mount and is secured to the transmission with the two mount studs and therefore moves when the transmission moves.. The 15 thou clearance is between the plate legs and the lower metal part of the mount which is mounted on the crossmember (which if memory serves me correctly is covered with a thin layer of rubber to prevent noise) and therefore limits the back and forward movement of the motor. The plate takes a real man to bend it. Go to online Old Chevy Manuals, Chevrolet Service News and Technical Service Bulletins Page 56 for a good diagram.

Awesome thank you, makes sence now!