That "speaker" hole is actually for the rear window defogger, a rare and not often ordered option!!
So, on to your build sheet! I'm going to go down the sheet from top to bottom, skipping the sequence number, SO number and such, and skipping the VIN as I think you have that decoded!! Now, if there is a number of letter in the box below an option box with a 2 digit number and a dash, it reads as a 3 digit number, so I'll give you the 3 digit number and the option!! So let's go...
YY1= Bronze Metallic roof and lower paint (1)= Monotone
B= upper door frame paint color= Black
31B= Horizontal Accent Stripe (B)= Black
P4X= Premimum Trim Level(Barracuda) (4)= Vinyl Bucket (X)= Black
31= 273- 1bbl
303= 4 speed trans
404= 3:23 axle
408= Sure Grip
421= AM Radio- 2 watt
487= Cigar Lighter
Tires (21)= 6.95x14"
509= Glovebox Lock
511=Map and Courtesy Light
548= Padded Sunvisors
564= Bucket Seats
565= Rear Armrests