Odd dimensions on a body 8 3/4

Hi Everyone,

I am putting an 8 3/4 into my 65 dart that has apparently been narrowed. It did not come with brake lines or the vent and tee. I received custom replacement axles from Dr Diff . I am now working on trying to get the brake line kit that will work for this rear end. However it appears the dimensions of the rear are slightly off. First off from drum to drum it measures 56 3/4 almost an 1 inch shorter than what it should be, second the vent hole location is 14 1/4 away from center., which is much further than the stock location. So I am going to have custom brake lines made for the rear end, that's not a problem. My question is should I be concerned about the axle being nearly 3/4 of an inch shorter than it should be? The axle needed to be replaced because one was shorter then the other by quite a lot. The leaf spring perches measure correctly at 43". The axle hosing is the same length on either side measuring from the center .- thanks