I just had to do this myself. But the closest matches were about 1" too short for both sides, so I ended up going 8" longer and cutting and flaring 1 end.

Hopefully you'll find a closer match with your 55.

1949 Canadian Built Chevy 1434 (3804 US equivalent)
In the Stovebolt Gallery

1949Chevy.com - Photo blog describing the teardown and restoration

AD Radio Rebuild