Nah, dude, that's not exactly correct.

Most chassis have the same wheelbase, a few do not. It depends on which chassis you buy. It's always a good idea to check chassis dimensions. Case in point: OfnaJL-10e. The wheelbase is 265MM. Most bodies are 255MM. Much of the time, when you run into this,"fudging" the distance between wheels can be done, without it looking bad, but it's a pain. You can also "stretch" a body using tension via body posts, but again, it's a pain.

Many (like Tamiya) have adjustable wheelbases. Those you just adjust for the body style you have, or are considering buying.

Then there are minis. Do not mistake a mini body for a standard body. They are both 1/10th scale, but minis are a few MM's shorter, wheelbase AND width-wise.

HPIon-road bodies are all 255MM. Since this is the standard for most chassis, just make sure your chassis is the same dimension, and you will be O.K.