Hey oldfart. Yes, I think that's what stumpy is saying.

If you don't have any bolts on the center of the rear end when you look at it from the back (no cover with bolts) , then you have an 8-3/4" and it will handle quite a bit of horsepower.

For gear ratio in the rear end, you have a couple ways to go.
1. There may be a little, thin metal tag on one of the rear end bolts with a number on it (the gear ratio). Sometimes they're missing.
2. If you believe the rear end is original, you can check the fender tag for a "rear end code" (D-something I think? D for differential?) Somebody who's sure chime in please. No code = "standard" rear end gear & you have to check online to see what's standard.
3. Lift up the rear of the car on jack stands, place a mark on the tire & ground, turn driveshaft by hand one revolution & count how many revolutions you got at the tire. Compare that number vs. possible gear ratios for that rear end & you can figure out what you have.