Genuine Laygear for Pre A plus mini including 1100/1300 except "S" & 1275GT with 4 synchro gearbox. Often stamped with part number
22G927 on.
The later type laygear has the same teeth count 15/20/25/29 usually mated with the later type mainshaft with 18mm nose for 1st motion shaft.
Later type laygear is
DAM3169-which takes larger bearings and will also need later type 3 step layshaft and correct end float shims.
Beware the close ratio gear for Cooper S had 3"diameter 25 teeth count and this gear is 1/8" wider diameter