Strange fluid on ground

[Stinger357]

Well despite all the troubles with my truck I have a new one appear now...on the ground under the middle of the truck is a medium size fluid of some kind, does not look like oil, nor water or it would have evaped. Someone told me it could be my diferential fluid or transmission fluid? Is there a difference? The transmission fluid level looks good by the stick, so not real sure what the fluid is.

 

[ncranchero]

 

[2000StreetRod]

possible fluids

ATF
Engine coolant
Engine oil
Windshield wash
Brake fluid
Differential fluid
Water (condensation from A/C)
Water (condensation from muffler with drain)
Battery acid
Fuel

 

[corkey]

what color is said fluid ?
red ?
brown?
gold?

 

[2TimingTom]

The transfer case and the transmission both use ATF.
The front and rear diffs use gear oil.
The engine uses motor oil.