1984 is right on the edge of the swiss bottom bracket era for Peugeot. Hopefully yours is past that experiment.

From Miami Jim's website:

"Bottom brackets can be either French, Swiss or British threaded. Left = adjustable = non-gear side. Right =
fixed = gear side.
French bottom brackets have 35x1 threading thats right hand threaded on both the adjustable (left) and fixed
(right) cups
Swiss bottom brackets have 35x1 left handed threads on the gear side (fixed) and right hand threads on the
left (adjustable) side

British bottom brackets have 1.370"x24 threading thats left handed on the gear side (fixed) and right handed
on the non-gear side (adjustable). 1.370" diameter threading converts to 34.798mm while 24 tpi converts to
a pitch of 1.058"