Rustproofing the only dif between '83 and '85?

The 'rustproofing' is just electrogalvanizing (ie: a thin electroplate coat of zinc) on the body metal. While it does elp prevent the spread of rust from paint chips, it's not as important as some would think.

After all, you're not planning to do a lot of driving on rainy days are you?

A lot of the older cars have the inside of the panels & undercarriage sprayed with Dinol, a heavy dark brown waxy 'rust proofing' coating. It works quite well.

Also, if it's been resprayed with a modern paint, especially a urethane paint like Chroma One, Imron, etc. then rust isn't likely to be an issue. They are very impermeable.

I've got a Euro '82 GTS QV & other than some minor bubbles that I took care of a couple of years ago, rust isn't a consideration.

Base your decision on the overall condition of the car & what you can learn of it's maintenance history. Don't forget too run a Carfax.

 

I believe the 83's used an air pump for emissions control, the 84-85's used an air injection system instead. (more reliable- no hp loss from driving air pump either)