Front stud or "pin" Mr Isuzu describes them as . 42331073 up to 9/'67. After this change 42331079. Same number as a PA 'Flo' on the rear. The rear stud is the same as the front before the change. [42331073]. Manufacturers do not give a reason for a change in part number. What the difference is I do not know. There is a note in the book where the later part will fit the old. BUT. The old will not be suitable for the new. The Bellett had considerable changes in the front hub and suspension area. Hubs. Knuckles. Control arms to name a few. Spline is critical if chasing non genuine. Overall length from under the mushroom head to the end of stud. 4 to 5mm is okay as long as it doesn't foul anything. Shorter is not advisable. Must have full nut on stud so as it will do the job.
Noticed that GT has different studs on front and rear and are not the same as the Sedan. Also KB series is different. Maybe because of 6 stud pattern.
I tried tonight to extract a stud from a rear axle to no avail.
Bit frightening I suppose when your trying to hit a pin punch with a hammer in the dark and only with a head mounted lamp as lighting. Not only that. It's 10.00 o'clock. 
Will have a go tomorrow in full daylight.
Dave.
