Want to install LSD or Posi traction in 2003 Tacoma Pre-runner

I recently purchased a 2003 Tacoma SR-5 Pre-runner, standard cab, short bed, Auto transmission and 2.7 engine. ( Vehicle had ONLY 10,103 miles and is in mint condition ) - Prior to this I owned a 2006 Tacoma V6 4x4 which served me well for 286000. thousand miles with only normal maintenance required.
I have driven my new to me 2003 Tacoma thru this years Vermont winter and have decided I could use either LSD or Posi-traction to help me get up the SNOW covered hills and back roads where I have lived for the last 55 plus years.
MY QUESTION IS: My Pre-runner is only 2-WD and I want to purchase and install a LSD or Posi-Traction into my unit and can not find an aftermarket unit for this. Can someone point me to a person who could provide me with a unit.
This is my rear axle code : B07A
B= 8" ring gear
07= 430 gear ratio
A= 2 pinion
Unknown items are - Axle diameter and number of axle splines - which seem to be important information when looking for aftermarket products.

Thanks - Crowhillvet

 

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