Hi I rencently purchased a 2007 4Runner. It has a button on the left side that has a X between 4 wheels. I think it is the locking differential. Is this correct? If so, is there any kind of upgrade (locking front or rear differentials) that are needed in addition to this?

thanks,

 

Read your owners manuel or push the button andtry to do a doughnut on thin water, you'll figure it out lol. For normal street driving a locking diff won't really do anything. If you want to race, tow, or go 4-wheeling a locking diff makes a huge difference.

 

the button is to lock your transfer case for a 50/50 split of the power. Same as pulling the transfer case lever on older models. I would not recommend using it on dry pavement as it can cause damage to the gears in your differentials. It should only be used in conditions such as off road or snow and ice.