How to colorize one texture array with another texture array?

I have a material with two different textures: One is the “main texture” in b/w, and one is a lookup gradient with two colors. Using a Param2D for each texture, it’s as simple as connecting the red from the main texture to the UV of the gradient texture to colorize the main texture.

However, now I am using texture arrays for both the main texture and the gradient texture, as they need to be swapped at runtime from a blueprint. Now I can’t figure out how to connect the two textures, since the uv in from the gradient texture is blocked, and I haven’t figured how to maybe combine the TexCoord and the main texture?

Figured it out myself: since the index for the Param2DArray is the 3rd channel from the UV input, I used an append3 to combine the r channel from the main texture as U and V and the array index constant (colArrayInd1) as the W channel.

i cant even make 1 texture array plug into a single non array gradient texture… just wont work… turns it into a solid color. Any idea?