I would stay with green or yellow....they can be be mixed and the yellow normally says it is universal. Unless you are gonna completely flush the system and switch to DexCool...I would not mix a DexCool branded coolant as it is not recommended to mix them. Some manufactures are using orange dye in their universal coolant so you can't go by color alone.
We probably have 10 different coolants at the shop to cover everything as we only use a coolant that is approved my the vehicles manufacture.
Cheap Thrills Off Road
2003 F-250 4X4 7.3 PSD Crew Cab