Re: 1976 75hp chrysler outboard pinnion retaining nut?
NO! I think for a 1976 engine 50 foot pounds is way too high. Your engine's lower unit has an upper and lower tapered roller bearing. The pinion nut sets the pre-load on the bearings just like a spindle nut would set the pre-load on bearings for a trailer spindle.
The factory recommends using a new pinion nut but, if you stake the flats or squeeze the nut in a vise to slightly deform it, it can be re-used. I seem to remember the number of 80 INCH pounds for the nut. This would account for the drag of the deformed threads on the drive shaft end and not pre-load the bearings excessively.
If you do not trust the number, set a new pinion nut the same way as you would set a trailer spindle. As long as there is zero clearance between the bearing cones and cups, you will not be far off and should not have problems.
Torque the nut to 50 FOOT pounds and you definitely will overheat the bearings with resulting premature wear and failure
