Tell me about my rear end please

[jlemler]

My fender tag has the A31 option which is:

3.91:High Preformence Axle Package
Available with 340, 383 4-barrel with 4-speed Manual Transmission or TorqueFlite. Not available with Air Conditioning or Trailer-Towing package.
•   3.91 Ratio Heavy-Duty, Sure-Grip Axle, 83/4' Ring Gear.
•   7 –Blade Torque-Drive Fan.
•   26" Hi-Performance Radiator with Fan Shroud.
•    Hemi Suspension.

My original rear end is missing.  I assume this is not a Dyna rear-end.  I assume it is just a basic 8 3/4 rear-end.  Can someone either confirm or correct my novice assumption, please.

[RUNCHARGER]

Yes: 8 3/4, newer style sure grip, 489 case, large yoke.