As far as I know 904 came behind 273 and /6, 998 were behind 318 in cars, 999 were behind 360 from 74 till it was replace by the A500 in A,B,C,F,M,J body cars and light trucks and vans. The 2.74 low gear set was used in 904,998,and 999 in 1978 through the late 80's to help cars get moving with...