I think we have communicated about your trailer a little bit via Facebook many weeks ago. This is a potentially unanswerable question as the Airstream Ohio factory only made five (5) Byam Traveler's between June and December 1953
. You have the only one known to exist at the moment, so there is nothing to compare to. I would advise taking photos of the axle and spring arrangement and posting them here. If they look old, they are likely original, but in the end we may only be able to guess until another shows up.
The comment about a torsion axle likely does not apply as Airstream did not convert to a rubber based torsion axle until the 1961
model year after the experience they had wth Wally Byam's 1957
gold trailer with it's prototype torsion axle during the 1959-60 African Caravan.
That said, I know Wally Byam was investigating spring based torsion axles in the late 1940s/early 1950s. I believe some of those may have been used on Curtis Wright trailers (maybe the Trail-R-Pal model?) in 1946 under Wally's design direction before he left Curtis Wright to restart Airstream in May 1947. I have heard a rumor that some of the early 1954-55 Wally Byam's Holiday trailers, that replaced the Byam Traveler and that began production in March 1954
, may have used a spring based torsion axle, but I have no first hand experience to confirm or deny this rumor. Or maybe I am just getting the Holiday's mixed up with Curtis Wrights.
I look forward to investigating this mystery with you if you can post some photos.