Couldn't find what I wanted at the junk yard, so I rebuilt the 3.08.
I found that axle retaining C-clip I dropped 2 years ago, when I put axle bearings and seals in it.
Well most of it anyway. It must have fallen deep into the case behind the pinion gear. It knocked some very small chips off 4 of the pinion teeth, but not where the ring gear contacts them.
Did a thorough cleaning of everything and replaced the pinion bearings/races. Having a bear of a time finding anywhere local which carries a crush sleeve which sets the pinion preload.
Now I am about to experience the joy of setting the pinion depth and backlash. Oh boy!