The 760 BDL Deluxe was introduced in 1966 and had Basket Weave checkering straight through till 1979, after which it became the Model 6. The only difference in the ADL versus the BDL deluxe was the basket weave checkering, so Remington put the hump on to be able to identify that the barreled action was a BDL deluxe because other than that there is no difference.
If on yahoo search you google "remington 760 basket" you will get many images and all the images with the basket weave checkering on the stocks have the hump on the receiver.