I recently purchased the Cowboys vs. Xenomorphs adventure for Mongoose Traveller and it’s a fun setting. So fun that I wanted more Period careers available to ‘flesh out’ the campaign.
I used the Drifter career as a template and created four Cowboy era careers (Cowboy Drifter, Cowboy Era Barbarian,  Cowboy Era Sailor/Pirate, Cowboy Era Charlaton.)
I also added Medieval Adventurer and Medieval Soldier careers that I have used in the past to finish out the Drifters from Other Eras career sheet.
Download the PDF: Traveller – Career – Drifters