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)
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)

Item 23 1H3275 is the rear seal to beused to be used in the rear extension for all of the MGA high starter gearboxes, including all Twin Cam1958-1960, MGA 1500 Com.(E)GD101 in Jan 1959, all 1600 and 1600-MK-II, and all 1600 "Deluxe" and 1600-MK-II "Deluxe" 1960-1962.

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