Stratman101,
At this point I'm a bit curious about your Alpine. With more info, someone may see something that will help you better than we've accomplished so far.
Is that five digit number your complete VIN? Or is it just a partial number?
Are your tachometer and speedometer the original equipment or aftermarket units? Have you checked the calibration of those units against a known reference?
What size are your tires and wheels? Any chance you could measure the rolling radius of the rear wheel/tire combo (center of wheel to ground)?
Is their any chance the previous owner said the the trans was from a turbo T-bird or Mustang? That would be about the worst unit to choose for your Alpine. (1352-018 Ford 1983-84 T-Bird/Mustang 2.3 L4 Turbo C R=3.76 1st=4.03 2nd=2.37 3rd=1.49 4th=1.00 5th=0.86)
In your rear axle picture looking at the drain plug, drive flange, and the way the parking brake is operated, I'd say your axle is original Rootes. More pictures of your Alpine can only help.
The bad is after trying some off the wall numbers, I think there is a good possibility you do have a 4.22:1. I think the only way to know for sure is to do some counting, if you are are willing.
Be aware this only works for an open differential. One rear wheel on the ground so it can't move and two wheel rotations due to the effects of the spider gears.
Safety first! Block the fronts wheels so no movement - might need readjustment.
Jack up one rear wheel enough to see the driveshaft from outside the car. Support the car in this position so it can't move or fall.
Transmission in neutral.
Mark the driveshaft by a stationary point so you can count rotations from outside the wheel (masking tape or light colored marker).
Mark the tire and ground so you can count wheel rotations.
Rotate the wheel/tire exactly two rotations while counting the driveshaft rotations. Try more than once.
If just under four rotations, then it's 3.89:1.
If about four and a quarter turns, then it's 4.22:1
Sorry for the length but I hope this helps,