[mssl72]

Here's what Chevy By Numbers says:

JD - 3-, 4-speed, Spec. High Perf., 396/375
KD - H.D. Clutch, Spec. High Perf., 396/375
KF - Turbohydomatic 400, Spec. High Perf., 396/375
KG - Spec. High Perf., 4-speed, Alum. Heads, 396/375
KH - Turbohydomatic 400, Spec. High Perf., Alum. Heads, 396/375
KI - H.D. Clutch, Spec. High Perf., Alum. Heads, 396/375