Thanks Bruno . I wasn't sure a quadrajet would fit in a Medium Flat Rate Box but I know it would fit into a Large Flat Rate Box .
The small flat rate box is currently $8.xx, the medium flat rate box $16 or $17.xx, and the "large" flat rate box is $21.xx. There are others, such as the "game" box, but they tend to not be stocked by most postal offices.
How does this work if someone has their part or car listed on here and somewhere else (eBay, Facebook, Craigslist, etc.)?