A998 Trans in '66 Dart

When I was messing with automatics for drag racing back in the 80's and 90's this is how it was explained to me by the guy who was building the transmissions. The 904 were original build for the slant 6, when the 273 V8 came out in 64 they made a new case for the 904 to fit the V8. Then in 67 or 68 with the new LA 318 they made a heavier duty trans and call it the 998( all 318 from then on came with 998). In 74 the 999 came out as an even heavier duty trans for the 360. 904 had 3 clutch plates, 3 clutch discs in front drum and 2 plates, 3 discs in rear drum, 998 had 4 and 4 in front, 3 and 4 in rear, 999 had 5 and 5 in front, 3 and 4 in rear. The lower gear sets and lockup converters came along at the end of the 70's early 80's for fuel mileage and the low gear set was there to get the cars moving with the 2.45 rear end gears they were putting in the cars. The 998 and 999 trans were made in non lockup and lockup.