Build Your Own Triple Drilled Differential Pinion Flange

After years of offroading with open differentials, I decided to take the plunge and buy a locker.

I decided to purchase a lock-right locker to install in my rear axle. Since my 1982 Toyota Truck is a daily driver, I opted to purchase a 3rd member from an auto wrecker so that I could take my time installing the locker and still be able to drive my Toyota. I found a 1987 Extended Cab Toyota that had new brake pads and rear axle seals, so I figured chances were good that the differential was well taken care of as well.

Once I got it home, I installed the locker following the How To Install A Lockrite Locker instructions.

When it came time to install this 1987 3rd member into my 1982 Truck, I realized that the driveshaft bolt patterns were different, and my 1987 driveshaft wasn't going to bolt up to the 1987 differential pinion flange.

After much research, I decided to try and drill a new set of holes in the pinion flange so that my 1982 driveshaft could be bolted to it. Here's how I did it.

1. Clamp the driveshaft flange to the differential flange. The center hole of the pinion flange will mate nicely with the center bump on the driveshaft regardless of the year differences of the shaft. This allows for easy centering and alignment of the driveshaft on the pinion output flange.


2. Find the correct drill bit and start drilling. Remember to use some oil, and take your time. It's a pretty big chunk of metal you have to drill through.


3. Once you're done one hole, insert a bolt, and rotate the flanges until the next on is in an easy to get to location. The bolt will help keep the flanges from getting out of alignment, and ensure that all 4 of your holes line up when you're done!


Total Time: 45 minutes

I had the differential on the bench, so it made things easier. If you are drilling the differential flange on the truck, it could take you longer.