/A/ versus /U@/: 22 pairs

ajar adjure 
baas boors
baas bourse
bar boor
barn bourn
barns bournes
guard gourd 
guards gourds 
kraal cruel 
lard lured
marred moored
marring mooring
Mars Moors
Moor mar
par poor
parley poorly
spar spoor
spars spoors
tar tour
tarred toured
tarring touring
tars tours