I understand how rank advancement works and I have Action cards that spell out a minimum rank needed; however, on the Reckless Dice podcast, I often hear the term rank 3,4 and 5 careers, yet none of the cards from the products I own (all but Hero's Call, Gathering Storm,Witch's Call, Signs of Faith and the POD products) state what rank a career is. What qualifies a career as rank 3 versus rank 4? I assume at a minimum an advanced career is rank 2.

Heroes Call states an optional rule/clarification where certain careers have a rank requirement to transition into.

As I recall off of the top of my head (and it could be off a little)…

Basic (Rank1) -> Intermediate (Rank2) -> Advanced (Rank 3) -> Elite (Rank 4)

 Thank you for the response. Is there a clarification in HC as to what careers are Intermediate, Advanced, etc.?

They are career traits and are listed on each career sheet.

 As dvang says, the traits are on the career sheets. There is also a fan-made career compendium available at rpggeek, which list the traits for all careers:

http://www.rpggeek.com/filepage/77002/warhammer-fantasy-roleplay-3rd-edition-comprehens