Triumph did have a separate part number for this weak 2nd gear bush, using the same bush as earlier gearboxes, however as the oil drillings moved over (see below), this kit has the oil groove moved over to account for the change.
Kit Contents-
1x129939-SL Uprated steel 2nd 'Top Hat' bush
2x153238 Uprated steel 1st and 3rd 'plain' bush
The associated washers used with this kit
1x129944HD 0.127" thick
1x129943HD 0.124" thick
Please take care to ensure the correct uprating set is ordered as gearboxes now have gone through so many rebuilds using parts from other TR's, as well as Stag, 2000, 2.5 PI, Dolomite, that it is important to know 'what you have' not what the car might have had initially.
To identify the correct up-rate set, look at the 2nd gear. If the oil drillings are in the base of the teeth use RTR1325-4. This gear set would have used a brass 2nd speed gear bush - very prone to the rim falling off the 'top hat'.
If the drillings are in-between the synchromesh dogs and the gear teeth, use RTR135-6E for gearsets originally from CD21769 to CR/CF 25000 (up to mid 1973) These gearboxes use the same brass 2nd speed gear bush as the earlier gearboxes with a central oil groove, but the oil drillings in the gears were moved such that the oil drillings no longer lined up with the oil groove in the bush. Triumph did not specify another bush to correct this. Our kit takes advantage of the opportunity to put in the oil groove in the correct place. This set is sometimes identified as being the equivalent of the Stag 2nd gear bush, for this Triumph used a plain bush and separate washers. This didn't work well as the gear could tip without the benefit of the 'top hat' bush rim to support it.
For gear sets from CR/CF 25001 onwards (mid 1973 on) use RTR1325-6L. This set is a direct replacement for the original parts (Triumph at last had got it right), but some materials used in current bush production are poor, so this kit is a direct replacement made from high-grade materials.