[CC69Rat]

67-Early 70 year model is 55.5" plate to plate.
70 (Late) + is 57" plate to plate.

So, Matt is absolutely right. If you have the early rear end, you'll be .75" (.75 x2 sides 1.5" total) different than say someone with a 70+ truck and 5" BS wheel. Ex. IF you were to get 5" BS, the wheel would sit further under the truck as it would on a 70+ year model rear end (since the width of the rear end housing is shorter more narrow) If you got the 4.5" BS on and early rear housing it would sit almost the same as a late rear with 5" BS. With the same rear wheel width. The difference is the outside would look wider .. The wheel would still be 9" wide regardless in both scenarios. You're just offsetting the wheel to compensate the overall width of the rear fenders so the tires 'fill the wheel well properly' .. Make sense?

Also, I have a Percy's Wheelrite I am willing to lend out of you guys need it. It will measure the wheel backspacing perfectly. Just help me out on shipping and I'll loan it to anyone who needs it.

Later ..