Hi Guys
I also found this interesting so I did a bit of research, here is what I found. I have covered most models of the Pz III Ausf E and on, Ausf A to D had completely different running gear.
There appear to be two basic designs E through G and J through N, F and G had both designs. The main difference is the return roller positions. All models had the off set tracks.
Here are the two basic designs. E to G had the return rollers as shown in Ausf G drawing and Ausf J to N had them as in Ausf L drawing. There are some combinations in Ausf F and G as shown later.
All comparision pictures have the right side reversed to clearly show diferent positions of road wheels, return rollors and suspension. Also note that the distance between the rear idler wheel, rear road wheel and rear return roller will vary due to track tension of rear idler wheel.
Pz III Ausf E.
Return rollers in same position on both sides, Road wheels and suspension moved forward on right side. Could not find a picture showing the rear return roller on right side so cannot comment on position of it and the rear suspension.
Pz III Ausf F
Early Ausf F has the the return rollers moved forward on the right side, but still at the same distance apart.
Pz III Ausf F Late
Ausf F late has the front return roller moved forward, note this model also has the later drive sprocket and idler wheel. This may have been a retro fit as the later model G (shown next) with the front return roller moved forward still has the early type drive sprocket and idler wheel.
Pz III Ausf G
Early Ausf G appears to be the same as early F.
Pz III Ausf G late with front return roller moved forward. Note late model still has early drive sprocket and idler wheel.
Pz III Ausf H
Ausf H appears to be same as late G, here you can clearly see the front and rear return rollers on the right side have all been moved forward, the center one appears not to have been moved. Note model still has early type drive sprocket and idler wheel.
Pz III Ausf J
Starting with Ausf J it looks like other changes were made to the position of the return rollors making a third design. Not to clear in these pictures, but betten shown in Ausf L pictures. Ausf J onwards were fitted with new drive sprockets and idler wheels.
Pz III Ausf L, M and N
Ausf L, M, N all appear to be the same. With the L model I was able to find pictures of the same tank from both sides with a scale pole on the road wheels which enabled me to get both sides close to scale. Here is were you can see the different positions of the return rollers on both sides.
Rollers A and C have both been moved forward on the right side and appear to have different distances between them and roller B, roller B may have been moved forward slightly as well, but this could be a photo enhanced position. The only way to be sure is for someone to measure them on a real Pz III.
Note on all models the suspension on the right side was moved forward in line with the road wheels. Also from the pictures you can see that the front return roller was lower that the others, even slightly on the earlier version although the scale drawing does not show it.
Hope you find this useful, I sure found it interesting.
Mike