Hi everyone! I need your help with solving my triamese cube. Its fused blocks are 1x1x3s. I can solve the two outer cubes like a siamese cube but I just cannot figure out the middle block.

Please explain in detail: I'm really just a beginner and this is my first time on this forum . Thanks!

Will check tomorrow because it is getting late here. Thanks again.

2 blocks are at RU and LD position.
step1 : center
step2 : E layer 4 edges
swap (UL , DR) and (RF , RB)
ALG1: U2 R U2
step3 : flip 4 corner
U2 R U2
This will destroy 2 edges of E layer
Save these 2 edges at lower layer (FD & BD)
Flip corner again
Restore 2 edges
Flip corner again.
step4 : M layer 4 edges
ALG2: M U2 M' U2
ALG3: M2 U2 M2 U2
ALG4: R2 U2 R2 U2 R2 U2
STEP5 : FLIP EDGES
ALG5: MUMUMU2 M'UM'UM'U2

Thx very much. I also modified the solution a bit to suit me.