I was wondering about that. Ford 9" are offset a ton, like 2 inches if memory serves me correctly. When I bought axles for a soon to be 8 3/4 I found they were the same length so center line of pinion must be off center to the car. I know ultimately as others have stated as long as CLs are parallel no issue, but it makes sense that the engine and trans are offset. I'll have to measure that to satisfy my curiosity.