741 case

Ok i found a rear for the dart it is out of a 70 duster.The car is a parts car with 90 thousand miles on it.The Canadian winter SALT did it in.Any way its 741 case with posi and 323 gears.How does this rear score is it a light duty no frills.The seller wants 800 Canadian,no **** that is close to what they go for here.