Lets talk cast iron 440 6 pack intakes. There are two part numbers 2946275 and 2946276. What is the difference if any between the two part numbers? I can't tell a difference on the car. What dates do you have of each one? Trying to find the earliest and latest casting dates, and what date they changed the part number on these. Thanks Moparts!

I'll start:
I have two 2946275 intakes with dates 6-17-69 and 7-11-69.
I have one 2946276 dated 8-20-69