PART NO.  SPL.PAGE  DESCRIPTION                                                           
1H3084    15.F.1    Extension -gearbox -Changed to 1H3149 Com.(G)A101 -
    Changed to 1H3273 Com.(E)GD101
1H3149    15.F.1    Extension -gearbox -Com.(G)A101 -(was 1H3084) -
    Changed to 1H3273 Com.(E)GD101
1H3273    15.F.1    Extension -gearbox -Com.(E)GD101 -(was 1H3149)
1H3273     16.F.1    Extension -rear -(gearbox assy, 1600 and 1600-MK-II)
1H3273     TC.F.1    Extension -gearbox -(gearbox assembly, Twin Cam)
1G3418   15.F.1     20  Bush (gearbox rear, early and mid 1500) -Fin.(E)GB51767
6K529     15.F.1    24 Bearing -rear extension(gearbox) -Com.(E)GD101 (high starter 1500 on)
6K529     16.F.1    24 Bearing -rear extension -(gearbox assy, 1600 and 1600-MK-II)
6K529     TC.F.1    24 Bearing -rear extension -(gearbox assembly, Twin Cam)
11G3147   15.F.1    21 Oil seal assy (early 1500 gearbox) -Changed to 1H3339 Com.(G)A101
1H3339    15.F.1    22 Oil seal (internal mid 1500 gearbox) Com.(G)A101 (mid 1500)-
    (Prev 11G3147 external) -changed again to 1H3275 Com.(E)GD101 (late 1500)
1H3275    15.F.1    23 Oil seal (internal late 1500 gearbox)  Com.(E)GD101 (late 1500)
    -(previously 1H3339)
1H3275    TC.F.1    23 Seal  Oil seal -(rear extension, gearbox assembly, Twin Cam)
1H3275    16.F.1    23 Oil seal -rear extension -(internal, gearbox assy, 1600 and
    1600-MK-II)
1H3275    TC.F.1    23 Seal  Oil seal -(rear extension, gearbox assembly, Twin Cam)
1H3275    16.F.1    23 Oil seal -rear extension -(internal, gearbox assy, 1600 and
    1600-MK-II)
CCN240    15.F.1    25 Circlip -oil seal -(gearbox rear, GB assy, late 1500)
CCN240    16.F.1    25 Circlip -oil seal -(gearbox rear, GB assy, 1600 & 1600-MK-II)
CCN240    TC.F.1    25 Circlip -oil seal -(rear extension, gearbox assembly, Twin Cam)
1H3304    15.F.3    26 Flange -3rd motion shaft -Com.(G)GD101 (gearbox, late 1500)
1H3304    16.F.2    26 Flange -3rd motion shaft -(gearbox, 1600 and 1600-MK-II)
1H3304    TC.F.3    26 Flange -3rd motion shaft -(gearbox, Twin Cam)
LWZ212    15.F.3    27 Lock washer (rear flange) -Com.(G)GD101 -(Prev. locktab 11G3226)
LWZ212    16.F.2    27 Washer -spring -nut -(3rd motion shaft flange, gearbox, 1600 and
    1600-MK-II)
LWZ212    TC.F.3    27 Washer for nut (spring) -(flange, 3rd motion shaft, gearbox, Twin Cam)
FNZ612    15.H.2    28 Nut for flange (differential input, 1500)
FNZ612    16.F.2    28  Nut -3rd motion shaft flange -(gearbox, 1600 and 1600-MK-II)91240
FNZ612    TC.F.3    28 Nut for flange -(3rd motion shaft, gearbox, Twin Cam)

Mid 1500 gearbox - Sep 1956 to Jan 1959

Early 1500 external seal, 1-inch 10-spline output shaft

< Mid 1500 internal rear seal, 1-1/16"10-spline output shaft

More information about this original type part, and some modern replacement type rubber lip seals, can be found in the gearbox tech article GT-111C