Need help! Transformer leads

Recently I bought a 117/6.3V transformer. It has 6 leads: 2 AC in and a ground, and 2 AC out and a ground. The problem is I don't know which wires are which, except the ground wires of course. The wires coming out one side of the transformer (in sequence)are: red, yellow, and black(ground). Then the wires coming out the other side are: white, black(ground), and white.

I appreciate any tips, ideas, or knowledge.

Ω

Measure the resistance. The 117V winding will have a higher resistance then the 6.3V winding.

Also, use the Ohmmeter to determine if the "grounds" are connected to the frame, or if they are infact taps on either winding.