rear end question?

[cyebo@xxxx]

Hey guys. I just found out that the Gremlin V8 rear end is a model 
#20 and the 4 and 6 bangers are model #15. I have been told that the 
#20 came out with 4.10 and other assorted gears as well as a limited 
slip. Whats the deal with em? Is this true or not? And can you still 
buy posi units and various gears for them? I want to buy one to swap 
out my weaker unit, so the width will fit right under my car. Also, 
to everyones delight I am going through the ads to try to find me a 
pure 100% AMC motor. now that I found some ads and different websites 
I seem to be running into a lot for sale. Can anyone tell me what a 
343 motor is? What did it comr from? how good is it? Thanks all, 
GREMLINMAN