What kind of rear differential came stock in the 79 F150 4x4 9 inch.
i was wondering if the locker had a specific name from the factory
or was it just just called a locker or limited slip? any info or a link
to some info would be great. i want to learn more about the stock diff.
i want to have it serviced and want to make sure i have the proper
info before i get in to it.

Thanks

 

So Im thinking you probably want to know the ratio. If you haven't decoded the tag on the door, start with that since it will tell you all that pertinent info regarding your truck. Im going to guess it has 3.50 gears since most 79 F-150's came from the factory with that ratio, but its not always the case. You might have a limited slim or even a locker again....decoding the tag on the door "should" tell you that assuming its all original. As for gear oil, a good 80-90wt will do the trick. As for a name??? Trak-Lok seems to be the most used term that I know.

 

Tag on door: Warranty Plate, located on the left door face below the latch.

1959-1980: If the AXLE code on the Warranty Plate begins with a letter: Limited Slip.

If with a number: No Limited Slip.

Limited Slip was an option, so not all vehicles have it.

Equa-Lok & Traction-Lok were both refered to as Limited Slip by FoMoCo.

Note: Verify if the VIN on the Warranty Plate matches the VIN on the registration.

People replaced damaged left doors with used doors. 99% of the time, they did not install the original Warranty Plate on the replaced door.