Here is the M53 Gasmask. This download include two variants. One normal pulled down mask and one pulled up. Enjoy.
For FiveM drag the files into EUP stream. If you dont have an EUP stream you can make one by creating a folder and in that folder placing an empty resource lua and a stream folder where the files go. If running on FiveM server you are required a key for the EUP to work!
Singleplayer:
Do this in OPENIV
Grand Theft Auto V
\update\x64\dlcpacks\mpstunt\dlc.rpf\x64\models\cdimages\mpstunt_male_p.rpf\mp_m_freemode_01_p_mp_m_stunt_01
Drag and drop into this folder. (Make sure to toggles it to a mods folder so it doesnt overright the orginal files).
Credits:
Max_