Athearn loco truck evolution

[Ray Marinaccio]

I got a few sets of old athearn trucks in a box of parts at the last show. I have a few questions as to when they were produced and how they fit into the evolutionary ladder.
First, I have seen Two versions of the Hi-F truck. Which was first?

I have seen photos of a gear drive with a metal case for the early GP9.

Are these trucks in the photo the first snap together trucks introduced in 1962? When were they discontinued?

 

[Ray Marinaccio]

Was this style of gearbox the next step?
When were they used?
Also, the sideframes on these are different from the next step in the ladder. They seem to be a different phase of flexicoil sideframe. What loco did they come on?

 

[Ray Marinaccio]

Was this the next step?
These have the steel plate gearbox sides with the pins for the gears.
I have seen this style with a plastic gearbox between the steel plates. When were they made?

 

[Ray Marinaccio]

These would be the 1973 version.

 

[Ray Marinaccio]

The 1984 version with inside bearings and plastic sideframes.
Do I have the order right? Or did I miss any?

 

[Russ Bellinis]

I'm not sure of the order, but if you look at the Blomberg (spelling?) trucks closely, you will notice that the ones with the metal side frames are correct for the early style trucks, and the plastic sideframes are correct for late style. The trucks interchange, so the plastic sideframes are correct for gp38-2, gp40-2, gp50, and gp60. The metal sideframes would be correct for f units, and gp7 & 9.