It seems like practically every 1800 convertible I've seen is a chop job someone did in the back yard. Volvo's are engineered such that a significant portion of the bodies strength lies in the roof - taking out that link leaves only the sills and transmission tunnel holding the front and rear together. Volvoville added braces but still the car is going to be a little whippy and very vulnerable to rust. I saw one original convertible that had totally collapsed in the middle because the sills had rusted (like they all do given 1/4 a chance).

An original Volvoville convertible might have some historical value - but Volvo folks in general just aren't the type of folks to shell out huge amounts of money for the truly rare. My own totally uneducated guess would be an actual Volvoville might be worth perhaps 50% over a coupe of identical condition (i.e. up to 15,000 in perfect condition) whereas other conversions would vary depending on the quality of the workmanship. Does it have a convertible top? If so - how well does it work. How solid/strong is the car - what reinforcements were added? A poor hack job could reduce the value significantly - a really nice one could be worth perhaps 25% over a coupe in identical condition?

A quick note on condition - at least in my mind RUST and condition of the bodywork is the most important factor in an 1800. Everything on the body is welded on and very difficult to replace. Every body panel has complex curves that are expensive to produce and align on the car. The bodies have complex sub structures and lots of cavities and are prone to rust. This basically means an 1800 that needs bodywork will cost more to restore than it will ever be worth (unless you are an accomplished auto body person with lots of spare time).

John Mc.