I checked my known cars and here what I have.
2 70 AAR with a.....52 coin
1 70 340 cuda(late) with.....52
3 70 440 b bodies with skid plate..... 79
1 70 440 cuda with skid plate.......77
1 70 Satellite 318 .....60

No coins on pre 70 cars and none on two 73 e bodies
No coins on my 318 e bodies.

Looks like 1970 was the only year that had confusing k frames.