The “Triumph TR3B” is an unofficial name given to the final version of the TR3, which was produced in 1962. It was offered concurrent with the TR4, which started production in 1961. The “TR3B” was a special short-production run in response to dealer concerns that the buying public might not welcome the TR4.

It had the body of the later “TR3A”. Two series were produced: one with a commission number preceded by TSF of which 530 were produced. Of these 530 the last 29 were built as Triumph Italia’s; one with commission numbers preceded by TCF of which 2804 were produced. Both series were partly produced in parallel. The TSF series were identical to the last run of TR3As, so with a two-litre engine and non-synchronized 1st gear transmission. The TCF series has the 2.138-litre TR4 engine. The engine is a straight-four, push rod, three-bearing, with wet liners. It has 9:1 compression and is very rigid. It was fitted with two H6 SU carburetors. It has 105 hp (78 kW) at 4,650 rpm and 172 N⋅m (127 lbf⋅ft) of torque at 3,350 rpm. It gets around 20 to 30 miles per US gallon. The top speed is limited to about 110 mph (177 km/h) by the gear ratio, unless it has overdrive. Electrically triggered overdrive (Laycock-de-Normanville Type A) was available as an option and operates on second, third, and fourth gears. Appearance is identical to the late US-version of the “TR3A”, with the same wider head light rims, for the rest very similar to the TR3, except for a wider grille and door handles. It weighs 2,137 lb.