I am going to take a highly educated guess here (Highly educated because the phrase "Been there, done that" applies)
He has a power gear rack and pinion system, and the pins are quarter inch bolts.. Hopefully he's been buying grade 8
When I was only a little bit younger I was buying those things by the dozen, literally, a couple times a year.. Someone dropped a hint and now.. Well the last dozen has lasted a LONG time.
Here's the hint.
IF there are THREADS inside the shaft, then it tends to shear the pins faster.
Get a longer bolt, One long enough that the smooth portion of the shank goes ALL THE WAY THROUGH.. Yes, you will have to put several thick "Fender washes" under the nut in order to get it to tighten down (By the way, Use nylock nuts)
And like magic they stop shearing as fast
Oh, I did have to re-dress and re-drill the square saft too. I (Thankfully) did not mess up the gear shaft or the transmission shaft.
Home is where I park it!