Any modifications that deviate from the data plate information would be subject to the owner's or buyer's taste. For example, if the car should be white, and you painted it red, it really doesn't matter as it can be changed back but a buyer may not want to spend the money on a paint job and move on to a white car that is per the data plate. On the other side of the coin, he may really like red and be glad and not worry about the "wrong" color.
A car that is all stock, appeals to more buyers because it is acceptable as it is and could be modified into anything a new owner wants. However, a modified car will be criticized by a smaller market base, as those who are looking for stock, will pass it by as needing work and money spent to make it original. Also those who are interested in a modified car are likely to say "I wouldn't have done it like that!" and need to re-modify to their liking.
In short, the change in value just depends upon the appeal and extent of the changes. Everything can be changed back if enough time and money is spent, but most modifications do not yield a profit when there are so many Little Birds on the market.
The documentation of it being built with dual quads must be provided as well as a source of the information stating 200 were produced. Having someone "say so" doesn't cut it to the informed buyer, you need documentation. There is a big possibility the intake was changed early on in its history by the first owner, or by the dealer before the car was first sold, and that is an entirely different story than being built (as in coming off the assembly line) with dual quads. Cars have been modified since day one and stories get embellished over the years. TARC (The American Road Thunderbird Club) provides invoices similar to what we think of as a "build sheet" for some 55's and most 56 & 57's for a nominal fee. This build sheet would prove beyond a doubt the car was really built with dual quads as it lists all the options and the prices.
If the original engine had factory dual quads, I wonder why the intake wasn't swapped onto the replacement engine? It certainly would fit and all the parts were available. If indeed so equipped, the greatest value would be to restore with original parts with attention to all the details.
The vin and engine numbers never matched on Fords until the mid 60's when it was mandated. The only numbers matching is the casting date on the engine block and heads should be prior to assembly by several months or less.
Get the original invoice from TARTC to know what you exactly are dealing with, then build, modify or return to stock, but most of all enjoy it!
Last edited by Joe Johnston : 07-07-2016 at 12:10 PM.