American Motors: parts, rear axle assembly, wheel drive vehicles

Question
Answer -
On 2 wheel drive vehicles such as yours they are not referred to as "front axles", they are called spindles. Look it up. Dana did not make them.
And even it they were called front axles, there are two of them, one on each side. So technically there are 3 "axles" by your definition. Gee, it ain't rocket science.

Response: Alright, you are correct now, in a way there are technically 3 axles in a RWD vehicle; each side of the rear diff. and the one long axle in the front. And I didn't mean to sound rude at first. Obviously there was a lot of miscommunication between us, and I apologize for my share of it.
So, I would like to put this incident behind us.

I do not have a model 20 rear diff., I don't know what it is. Is there an easy way of finding out?
Can I just remove the whole rear diff. and replace it with a model 20?
What other hoods fit on my concord, other than a hornet?

I apreciate the time you take to offer your assistance. Thank you.

Answer
You can remove the complete rear axle assembly and replace it with one form a Hornet, Gremlin, Spirit or Concord with a V-8 engine. The ring gear diameter on a V-8 AMC differential is 8 7/8" in diameter, the one in your 6 cylinder is 7 9/16" diameter. All V-8 equiped AMC cars use the larger rear differential. The difference is how wide they are. Javelins are wider than your car, by just a little. You could use a rear end from one of these, but your rear tires would be sticking out farther.