Email me a picture of that crossmember and I'll tell you if its '54 or '55 1st, or if its the earlier one. Once you've seen both they are easy to identify.

Do you know this frame is a Chevy or could it be a GMC?

This page has some pictures that will help sort it out.

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...