Original
Moss four-speed with Laycock overdrive at 0.778
Fitted
Tremec T5 WC five-speed, fifth gear 0.82

Differential ratio: 4.09 changed to 3.54

ConfigurationSpeedEngine speed
4.09 diff, overdrive70 mph2,800 rpm
3.54 diff, Tremec fifth70 mph2,500 rpm