I have an intermittent problem with the ZF S5-42 I swapped in along with the 7.3, I believe it's an 89 model. Every now and then it just will not go into reverse. I know there is a lockout to keep it from going from 5th to reverse, but is this a normal failure, easy fix or sign of larger problems?
It's just that it happens at the most inconvenient times, like when trying to back a trailer into a customer's driveway, or when I get lined up across a road to back into a turnaround spot, etc.