needing a new rear end and advice

sorry guys lost my password but its a 318 with 360 heads and a mild cam what the guy told me and no its not a track car just my driver but i do like to squeal my tires and take off at red lights

i never plan on going any crazier with the motor i like the 318 an d don't want to sink a whole lot of money in to it how much do these rear ends go for

i think the 7 1/4 will live a long time in that car. down the road if you have any issues stick a 8 1/4 in the thing.