Difference in front drums from 68 to 69?

[60ShortStepGMC]

Can anybody confirm that 68 front drums had the "anti-vibration spring" while the 69 front drums did not?

For that matter, can anyone tell me if there's a significant difference between the hubs and drums for these years?

A while back I purchased some 69s (per seller) with the "a-v" spring. Recently someone indicated that only 68s came with the spring. Just trying to learn what's correct, and then if it really even matters (because, basically, they may be interchangeable?).