In 1942 Parker transitioned from the aluminium Speedline filler rod to a plastic filler rod due to wartime material restrictions.
This change also coincided with a redesign of the blind cap, which became more rounded in profile.
These models mark the final phase of the Speedline era before further post-war redesigns.
The plastic rod is typically darker and non-metallic in appearance.
Most plastic-filler Speedlines date to 1942.
Check:
Some transitional examples may combine:
These combinations are highly collectible.
Images coming.