1970 duster clone. need opinions.

is there any way i can tell just buy looking at it what engine it is? and how can i I.D. the rear end. and as of today the guy is putting in new carpet and cleaning it up better. i looked all under the car everywhere and there was no rust anywhere. i even got to see the floor pans when he was swapping the carpet and they look good. and i honestly dont know if it was an origanol v8 car or not. i have lots more pictures of it if anyone wants to look over them and see if they can spot some stuff. i am trying to sell my fox for $6500 btw.

and as far as site karisma you guys deffinatly rock. i have been on a few mustang forums and there is always someone coming out trying to put you down, and i have seen none of that on here. everyone has been nothing but helpfull. and as far as statement's about the car, yall put them across where one can tell your not bashing but giving helpfull advice. and i thank you all for it. even if i dont get this car im gonna continue my search for a nice A body and will deffinatly be back on here.