Isn't D4 3:73?
Actually, I don't even see D3 listed:
Explorer
Door Code/open or limited slip/ratio
41....….…… Open 8.8"…...….. 3.27
42..…..……. Open 8.8".….…... 4.10
43..……..…. Open 8.8"…..…... 3.08
44..………... Open 8.8"….….... 3.73
45..…..……. Open 8.8".….…... 3.55
46..……..…. Open 8.8".…….... 3.73
D1..……..…. L/S 8.8".…...…... 3.27
D2...…..…… L/S 8.8".…...…... 4.10
D4...….……. L/S 8.8".…...…... 3.73
D5..……..…. L/S 8.8".……...... 3.55
Or is the code different for a 4x4?