Need 07 rear locker help

I have a 07 Tacoma base model 5 lug with a 4 cylinder, I am trying to find a rear locker for it, does any one know where I can get one and what model #, I have been trying to figure out what axle I have in my truck but there is no information on the base models, any info will be a great help. Thank you.

 

http://www.tacomaworld.com/forum/5-lug/192949-5-lug-regearing-bs-info-3.html#post4724258

 

X2

 

From what I can find from everyones help is that I have a 8.4" rear end, does anyone know if it is the same as the srunner or xrunner, I still cant find a locker that says it fits a base model, is it also the same as a 4X4 rear, not the housing or axles but the third member.

 

Thank you whippersnapper02 thats just what I needed to know.