I found a new rear end for a good price. 742 housing with 4.10s posi type unit. I was wondering if the 742 housing will replace the one in the back of my charger now because i am not sure if the length is the same or if i should just take the carrier assembly and place that into the center of the rear already under my car. Also is there a way i can quickly verify that it is a 8 3/4 rear under my 72?

 

If there is a plate you can take bolts out of (usually facing the back of the car), it is not 8 3/4. If the bolts are toward the front of the car, it probably an 8 3/4. Check out the pic, this is an 8 3/4.