I remember reading something about the markings they used but can't remember everything. I believe it was just their way of identifying the different converters for different applications. Such as a converter with orange markings was for a 318. A converter with blue markings was for a /6. Since your engine was a 318 and there was no such thing as a performance 318 back then they only used one converter on it I believe. Unlike a 383 that had a std. and a magnum version that came with a high stall converter. I highly doubt yours is anything special.