#1. Who knows the facts about the production numbers of the Schwinn Klunker 5.
Answer: Nobody.
#2. The first month produced in 1978
Answer: Having a list of all the Klunker's build dates stamped on the head badge is the only way to figure that out.
#3. what the six number serial number represents following the two letters.
Answer: The serial numbers are stamped on the bikes components prior to being used in building a frame. The date associated to the serial number is the date that number was stamped. That's all it represents, it's a serial number.
#4. How many were produced in the color schemes?
Answer: Nobody knows how many were produced in the (2) colors.
Probably repeats of what others have said and I'm not sure what else can be said. There are no records. I will add that there are quite a few fakes out there. If one is Blue or has a Klunker "decal" on the chain guard verses being painted on, it's a fake.