Perusing old threads about this rule (16.3.5), I found contradictory information! So I must re-ask in hopes for clarity.
Do you place the Devastation marker in the Lend-Lease Track's rightmost empty space (eg, you'd place Devastation in space 5 even if the Soviets only had a marker in space 1) or the leftmost empty space (eg, you'd place the Devastation marker directly to the right of the rightmost Soviet unit)?
(The second option makes more sense to me but that' not what some previous threads indicated.)
The rules (v1.02 is what I have I think) state that you place them starting in the rightmost space, filling in to the left with additional Devastation markers.