You can grab a set of 11" backing plates from pretty much any rear wheel drive mopar on up into the 90's. 8.25, 8.75 and 9.25 rear ends all used the same bolt pattern on their axle flanges. So hit the junkyard and grab a set off a truck/van or older RWD mopar. The 11x2.5 is the most common, and cheapest. I believe, but am not 100% sure, that the 11x3 uses the same backing plates as the 11x2.5...just a larger shoe.