Found a way to allow any colored variation of the 2007 movie starscream mold to have realistic replicas of the G1 Seekers standard weapon a null ray.
But this trick is unique, i did with few Lego Brick. And it works well in both modes.
You'll need(
you'll need twice the described ammount if you intend to use this on more than one 2007 jet voyager class starscream mold)
2x of this piece

4x of these black pegs

and lastly 2 of these angle connectors(they are needed to lock the pieces in place to your Seeker infantry as instructed)

-NOTE- Repeat twice for both arms
1- Grab your the intended transformer, (in my case i only had 2007 movie thundercracker) unfold the triangular missile rack and make sure to empty them if any missiles are in there.
2- First take the two long pieces of black pipes and attach one 3 cm long pegs, in each end on both pipes.
3- Grab one gun and attach it in the hole which is closest to the arm and elbow assembly of the transformer
(if done incorrectly the full assembled version will flop around) Once you have it the right hole... grab one of the angled pieces and connect it to the remaining end of the peg sticking out of the missile rack but make sure to fit it tightly.
Repeat twice for both arms
Also for decoration it works wonders if you add missiles in the remaining holes in the missile holders...and if you have movie 2007 swindle(orange car drone) or any variations of him you can take his arms and plug them into the tight space between the missile cannons at the end of his arms to give your seeker fists.
I might make pictures of my thundercracker later,but im too lazy to get my camera right now.