Jarod,

See from page 71: http://www.history.army.mil/books/Li...nfantry.htm#10

Companies would be lettered with the 1st Battalion having four companies: Three rifle companies: Able, Baker, Charlie with Dog as the Heavy Weapons Company.

2nd Battalion: Easy, Fox, George with How as Weps.
3rd Battalion: Item (J was not used as a company letter), King, Love with Mike as Weps.

Here's the 1952 TO & E for an infantry battalion: http://cgsc.contentdm.oclc.org/cdm/s...9/id/831/rec/3

Here's the 1950 TO & E for an infantry regiment:
http://cgsc.contentdm.oclc.org/cdm/s...9/id/843/rec/4