Ja Perm
A 1×2×3 block is already solved: a full bar of three plus a two-sticker bar on the next side. Ja and Jb are mirror images.
R' U L' U2 R U' R' U2 R L10 moves · Probability 1/18 · Corners UBL↔UBR · Edges UL↔UB · Mirror: Jb Perm
Setup: apply these moves to a solved cube to reach this case
L' R' U2 R U R' U2 L U' ROther algorithms
Dashed keys are AUF: a U turn that lines the top layer up with this algorithm.
U'L'U'LFL'U'LULF'L2ULU'