Pseudomonas aeruginosa utilizes dual flagellar stator systems for motility; and 15 dual stator bacteria possess auxiliary flagellar rotor ring components in their periplasm. 16 In P. aeruginosa MotAB and MotCD comprise the dual stator system and MotY is the 17 auxiliary periplasmic ring component. We investigated motility of strains and their 18 isogenic ∆motY derivatives which expressed chimeric MotB/MotD periplasmic domains 19 and characterized differences in motility behaviors. We found in general motility is 20 severely impaired in strains carrying motY deletions and which express C-terminal 21 periplasmic regions of MotD, compared with strains expressing MotB C-terminal 22 counterparts. Motility in soft agar is slightly increased in strains expressing N-terminal 23 MotB transmembrane domains and MotD C-terminal periplasmic plug, PGB, and extensions, but motility is severely impaired in ∆motY strains. Addition of the extended 25 24-residue C-terminus of MotB to the C-terminus of MotD does not significantly affect 26 either motility or compensate for the deleterious effect of motY mutation, but does 27 significantly increase motility in motY+ backgrounds. The soft agar motility results for 28 organisms with wild type MotAB stators was not different from those with MotAB stators 29 carrying 24 residue MotB C-terminal deletions; however, motility of these mutants was 30 significantly lower in motY mutants compared to motY mutants expressing wild type 31 MotAB stators. We discuss contributions of stator functional domains to motility and the 32 effects of ∆motY deletion. Lastly, we speculate on possible mechanistic roles for the two 33 stator plug types based on thermodynamic considerations related to differences in 34 composition of the hydrophobic surfaces of the two amphipathic helices.