Those chevrons are usually white or black in colour depending on the vehicle's colour for contrast using Mk1 Eyeball or using thermals. I suggest use white. The number you see either denotes which platoon the tank is. IIRC the Marines use[d] a similar but different system than the Army with these chevrons etc.
To give an example my 1/35 M1 "Another Episode":
Chevron pointed up - Alpha Company
Small square dot inside - First Platoon
Tank's bumper code is A13 - Alpha Company, 1st Platoon, 3rd tank
Chevron pointing up with number 51 inside - 1-64 Battalion, Alpha Company, 1st platoon (note: this chevron with numbers inside is different from the other chevron that has dots inside. The former is for battalion, company, platoon; the latter is simply a reflection of the bumper codes so company, platoon, tank) (2nd note: AFAIK only seen during OIF 2003)
Three red rings/stripes around the bore evacuator of the gun - 1st platoon, 3rd tank
The system I guess changes from time to time. The above is found during OIF in 2003.
Kei is the commander of Saunders, right? So this is a command tank, yes? I don't have my notes on hand now to designate a company commander's tank but will let you know asap.