Which are correct KYBs for rear?

[rickf]

The various sources for KYB application info are ambiguous, I hope you can help.

At the root of the question is another question: Is the trailing link / coil spring rear suspension on 67-72 C10 the same as 64-66 C10 ?

Catalogs are showing KYB KG5416 as correct rear shock for 67-72 C10 with coil springs, and show KG5419 for 67-72 with leaf springs.

By year, the catalog shows KG5419 for 64-66, with no mention of coild or leaf.

Under the shocks, both KG5416 and KG5419 list 64-66 C10, but still no mention of coil or leaf.

I am guessing the 64-66 is same construction and configuration in the rear as the 67-72 with coil springs, so I should get the KG5416.

Does this sound right?
Does anyone know if dampening is actually different, or is it just length?

-rcf