Here are couple codes from my six shooter run

Gentleman - J5KJ##K7R4WX
Preacher -M03XCJ7V3VM1
Brigand - JN1K72FKMWN1
Mercenary - 40P5SFPJ2SCN
Thug - WR22#BLP84R3
Navvie - 1NLMD78#LWXF

Cant confirm they work, but let me know whether they work or not.
General tips

- Preacher is best companion because of first aid kit.
- First aid kit is the best special for yourself. Leave world food for companion.
- You wanna change to shield in the last shop menu for those pesky fireballs in 4-4. Helps also for chaos engine but I noticed they dont protect from blue lasers.
- Gentleman was awesome companion for preacher. Fast, smart and firepower.
- Might be wise to fill you healt in the end of levels before shop. Using money to buy health in shops should be mininal.