1949 3100. I have a 350/TH400 in place on the frame using the front engine mounts from Classic Performance Products.
I did not touch the the center riveted-on crossmember.
I moved the original bolt-on transmission crossmember back 3 1/2 to 4 inches in order to line up with the rear mount of the TH400.
I placed the rubber transmission mount between original transmission crossmember (in its new, rearward location) and the transmission.
I mounted the cab to check for clearance and the cab hit the transmission.
I only have 3/8" clearance between the center riveted-on crossmember and the bottom of the transmission, preventing me from lowering it any more to facilitate cab clearance.
I decided to alter the contour of the bottom of the cab, moving it one inch rearward (easy to reverse if someone in the future wants to go back to the original shape).
The carb mount surface is now parallel to the floor.
So what is my question?
I have read many posts about this modification and none of them described it as being as simple as this to do.
There are posts referring to removing the center riveted-on crossmember, using aftermarket rear crossmember or notching out the original one, or cutting out a huge hole in the cab.
What am I missing?
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission