List of all of the ranks and what they unlock

Lvl 01 (Private) (Classes Grenadier [Assault], First Recon [Sub Machine], Overwatch [Light Machine Gun])
Lvl 02 (Private I) (Scout Sniper Class)
Lvl 03 (Private II) (Riot Squad Class)
Lvl 04 (Private First Class) (Create a Class)
Lvl 05 (Private First Class I)
Lvl 06 (Private First Class II) Painkiller Death Streak
Lvl 07 (Specialist) Throwing Knife Equipment
Lvl 08 (Specialist I)
Lvl 09 (Specialist II) SCAR-H Assault Rifle, Hardline Tier 2 Perk
Lvl 10 (Corporal) Killstreak Rewards
Lvl 11 - (Corporal I) Tactical Insertion Equipment
Lvl 12 - (Corporal II) Vector Sub Machine Gun
Lvl 13 (Sergeant) Scavenger Tier 1 Perk
Lvl 14 - (Sergeant I) Thumper x2 (Launcher)
Lvl 15 (Sergeant II)
Lvl 16 (Staff Sergeant) MG4 Light Machine Gun
Lvl 17 (Staff Sergeant I) Scrambler Tier 3 Perk
Lvl 18 - (Staff Sergeant II) AA-12 Shotgun
Lvl 19 (Sergeant First Class) Blast Shield Equipment
Lvl 20 - (Sergeant First Class I) TAR 21 Assault Rifle
Lvl 21 - (Sergeant First Class II) Bling Tier 1 Perk
Lvl 22 - (Master Sergeant) G18 Machine Pistol
Lvl 23 (Master Sergeant I)
Lvl 24 (Master Sergeant II) P90 Sub Machine Gun
Lvl 25 (First Sergeant) Cold-Blooded Tier 2 Perk
Lvl 26 - (First Sergeant I) .44 Magnum Handgun
Lvl 27 - (First Sergeant II) Martyrdom Death Streak
Lvl 28 - (Sergeant Major) FAL Assault Rifle
Lvl 29 - (Sergeant Major I) Ninja Tier 3 Perk
Lvl 30 - (Sergeant Major II) Stinger Launcher
Lvl 31 - (Command Sergeant Major) Claymore Equipment
Lvl 32 - (Command Sergeant Major I) AUG HBAR Light Machine Gun
Lvl 33 - (Command Sergeant Major II) Danger Close Tier 2 Perk
Lvl 34 - (2nd Lieutenant) Striker Shotgun
Lvl 35 - (2nd Lieutenant I)
Lvl 36 - (2nd Lieutenant II) WA2000 Sniper Rifle
Lvl 37 - (2nd Lieutenant III) SitRep Tier 3 Perk
Lvl 38 - (1st Lieutenant) M93 Raffica Machine Pistol
Lvl 39 (1st Lieutenant I) Final Stand Death Streak
Lvl 40 - (1st Lieutenant II) M16A4 Assault Rifle
Lvl 41 (Captain) Last Stand Tier 3 Perk
Lvl 42 - (Captain I) Ranger (Double-Barrel) Shotgun
Lvl 43 - (Captain II) C4 Equipment
Lvl 44 (Major) Mini-Uzi Sub Machine Gun
Lvl 45 (Major I) One Man Army Tier 1 Perk (Replaces Secondary)
Lvl 46 - (Major II) M9 Handgun
Lvl 47 - (Lieutenant Colonel)
Lvl 48 - (Lieutenant Colonel I) ACR Assault Rifle
Lvl 49 (Lieutenant Colonel II)
Lvl 50 - (Colonel) Javelin Launcher
Lvl 51 - (Colonel I)
Lvl 52 - (Colonel II) M240 Light Machine Gun
Lvl 53 - (Colonel III)
Lvl 54 - (Brigadier General) M1014 Shotgun
Lvl 55 - (Brigadier General I)
Lvl 56 (Brigadier General II) M21 EBR Sniper Rifle
Lvl 57 - (Brigadier General III)
Lvl 58 (Major General) TMP Machine Pistol
Lvl 59 (Major General I)
Lvl 60 - (Major General II) F2000 Assault Rifle
Lvl 61 (Major General III)
Lvl 62 - (Lieutenant General) Desert Eagle Handgun
Lvl 63 - (Lieutenant General I)
Lvl 64 - (Lieutenant General II)
Lvl 65 - (Lieutenant General III) RPG-7 x2 Launcher
Lvl 66 - (General)
Lvl 67 - (General I) Model 1887 Shotgun
Lvl 68 - (General II)
Lvl 69 - (General III)
Lvl 70 - (Commander) AK-47 Assault Rifle

The ones that are blank I'm not sure what they unlock...