These are the part numbers from the Mopar Chassis book for A999 H.D. trans for 360( they first appeared in the 1974 360 4brl cars) All of the part# below had 2.45 first gear sets as far as I know, except the P parts trans that could have had the 2.74 gear set( I do not know for sure)
74-75 PN3681844 A999 non lock-up
76-77 4028465 A999 non lock-up
1978 4028878 A999 non lock-up
4028815 A999 lock-up
4058111 A999 lock-up
1979 4130515 A999 lock-up
4130645 A999 lock-up
P parts trans/ P4130400 A999 non lock-up(with man. v.b.)
PN3743382 A999 5 disc front clutch retainer, 1942403 front clutch plates(5 required) 2205203 front clutch disc(5 required)
My book only goes up to 1979 so this is all the part numbers I can give for the A999 and this same book says the A998 trans came out in 1968( I thought I was told 67 I was wrong) as an H.D. trans for the new LA 318. I had 3 of A999 transmissions back when I was racing my 69 GTS Dart W2 360(3681844) that was built by Turbo Action with a low gear set. I put that one in my 80 Mirada but the new W2 372 engine and the low gear set didn't like to play nicely together, so I found another(844) in a 75 360 Cordoba( which was a standard 2.45 gear set) and put it in the Mirada. Soon after I pick up a spare A999 part # 4028465(2.45 gear set) and If I remember right it came out of a 76 Plymouth Fury 360 2brl . My trans guy told me at the time what cars with 360 engines to look for transmissions in.