Roman529
Moon Runner / The 3 AM Crew
Linebackers and fullbacks/running backs are permitted to wear numbers in the 40s.
They do exceptions for like when they run out of numbers, or when players petition the league for a certain number:
http://en.wikipedia.org/wiki/Uniform_number_(American_football)
Numbers 1 to 19 are worn by quarterbacks, kickers, and punters. Since 2004,[3] Wide receivers are also allowed to wear numbers between 10 and 19 if they choose, even if a number from 80 through 89 is available.
Numbers 20 to 49 are worn by running backs, tight ends (40-49, when an 80-89 number is unavailable), cornerbacks and safeties.
Numbers 50 to 59 are worn by linebackers and defensive linemen and offensive linemen.
Numbers 60 to 79 are worn by members of both the offensive line (the tackles, guards and centers) and defensive line (the defensive ends, defensive tackles or nose guard).
Numbers 80 to 89 are worn by wide receivers and tight ends.
Numbers 90 to 99 are worn by linebackers and defensive linemen. In effect since 1984.
Numbers 0 and 00 are no longer used, though they were issued in the NFL before the number