7.25 drum to drum measurement

Oh boy.

A ‘67 7.25” may not be the same width as a ‘73 7.25. The BBP 7.25’s are not the same width as the earlier SBP 7.25’s.

The 57 1/8” measurement is the SBP 8 3/4 width, which definitely is NOT the same as any of the A-body 7.25’s.

Using a tape measure and going over the center hump will make your measurement longer than the actual width, potentially by a significant amount. None of the A-body 7.25’s are wider than a SBP 8 3/4, so the 57.2” measurement is totally inaccurate.

And as for “measuring 100 and getting 100 different measurements”, that has not been my experience. I’ve measured dozens of Mopar 8 3/4’s, and all them were less than 1/8” from the specs in that list I posted when measured correctly. Their width is somewhat critical to the function, and unlike body tolerances they were held pretty tight.



Your ‘73 could be either SBP or LBP, depending on whether or not it came with factory front disk brakes. In 1973 the disk brake cars went BBP, and all factory V8 cars got front disks in ‘73. A /6 car could be drum/drum, and those care remained SBP. So, just knowing that it’s a ‘73 with a 7.25” doesn’t confirm which bolt pattern it is.

You can definitely use an axle wider than the A-body 7.25” regardless of its type, but your clearance to the quarters also depends on your wheels backspacing. And if you’re going from SBP to BBP that could be changing!
Thank you, again. I have called my shop, and booked her in, as they are specialists in chassis dynamics and will measure everything, including space to the quarters and advise on tyre widths and we can address the axel width. I think this is too important for me to make a guesstimate - especially if we widen the axel.

@72bluNblu - out of interest, what are your preferred wheel and tyre specs (if you're not using stock wheels). I have a 450+hp 360 Magnum going in, set-up for daily driving but with more power low down - dynamically, on the street, the aim is punching in and out of corners and some autocross down the line, once a Tremec goes in - any of your excellent advice always appreciated.