According to Zcar dot com and Hybridz dot org since i was in need of an answer, i have found that near all parts are identical. Nearly 90%. Most body pieces will interchange, but i am unaware of minor differences (if any) in the body. I myself am going up to look at a 79' 280zx to be a parts car for my 82' 280zx. What i do know positively is 2+2 and coupe's body parts are not interchangeable from the firewall back. But everything else such as interior should be. The hatch from a 2+2 and coupe may interchange as well, but i am not sure of that. So in conclusion if you are considering buying a parts car for your year car X, and the parts car being a previous year car, it should be mostly interchangeable. The reverse way, i am unsure of though.

-Heath

Generally for an automatic 5 compleatly empty, but remember when you drain the pan the fluid from the torque converter doesnt come out so a normal change sould be more like 3.5 qts. On a manual drain the fluid into a bucket and measure how much came out, then replace the same amount with new fluid.

on a Nissan 280zx from 1979 to 1981 everything on the entire car is the same even down to the body doors and hatch

For the front right, you just have to take out the glove box which is just unscrewing a series of screws. This will allow you to see the speaker and unscrew from below. I'm lost on the front left. I've replaced the rear and front right in my 1981, and am stuck on the front left.