904 transmission ID
The PK4028814 was installed with 318. I believe the 999 was only behind a 360. Here are the 999 numbers according to the Direct Connection Chassis Book.
'74-'75=3681844
'76-'77=4028465
'78=4028878 non lock-up
4028815 lock-up
4058111 lock-up
'79=4130515 lock-up
4130645 lock-up
Hope this helps.