a body rear end ? 8 3/4 vs dana 60

Don’t mix up backspace and offset, they’re totally different measurements.

And without listing your car model, suspension modifications, axle width, rim dimensions and tire size just giving your backspace could totally mislead someone. A 3.5” backspace would be a mess on a stock width axle unless you’re talking about a 6” wide rim and skinny little tires. Or a massive rake and tires hanging out in space like a 70’s street freak.