John's right, the 83 is just a much better build bike, more like the 84 500, better (longer rear shock) better frame with removable rear sub frame, better gearbox (but a bit stand alone for parts).
Having said all that it will be a lot harder to find a good 83 than 82.
I ride my 82 a bit and do like the 4 speed but is a bit more old school than the 83 or 84, 84 is a great bike (more like a 250 to ride) but now getting very heavy on the older gearboxes.
Shane