coarse thread vs. fine thread strut rods
Here are some pictures as you can see the coarse threaded are shorter from flange to flange between the LCA and the K-member for the use of larger bushings.
The space where the bushing goes is longer for the use of a two piece bushing on the coarse threaded rod.
Although there are two piece bushings available for the early rods as well. But they are a lot smaller and do not require a steel sleeve.
That is the way to tell the difference. Later bushings and rods use a steel sleeve between the washers on the coarse threaded rods. the early fine threaded rods do not