4 D-Cell Maglite Mod HELP!

[Barney Rubble]

I'm putting together a Maglite mod and I've ran into a problem. I cannot find a female cap to fit the end of my replacement cylinders that I plan to mount below the main flashlight using Maglite flashlight wall mounts. See the red circle on the photo for the site where I need the mystery cap.
I'm hoping the pictures are worth a 1000 words as they say. Please help me if you can. Thanks for your time guys. I look forward to getting into this forum. Never belonged to one before.
The blue flashlight picture is just an example of how the replacement cylinders are basically meant to be used.
✌🏼🖖🏼🙏🏼 Thanks!!

Update: one reasonable work around for my problem posted above in a Zoro 6VFN2 Mech Expansion plug,turn-tire, 1-1/4". Fits great inside the cylinder body of the D-cell Maglite male end (red circled part of the picture above). I'll post a picture of the model I ordered(see enclosed picture) The actual piece is in the process of being painted gloss black.