63 Dart rear axle relocation.

I just picked up a 63 Dart GT that I will be doing a full rebuild on. I plan on mini-tubbing and relocating the leafs inboard. My question is someone told me that the axle has to be pushed back approx. 2.5 inches to center it in the wheel wells, can anyone shed some light on this?

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I put an 8 3/4 with bbp Moser axels in my 66 Dart,also have 255/60/15 on the rear.I didn,t minitub or relocate any thing!

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