Technically.....that's a TR3A (the wide-mouth grill being the primary visual difference). The TR3 had a more narrow grill that was set back under the T R I U M P H lettering and the badge. Brought a non-running TR3A home on a trailer for my 16th birthday.....rebuilt the motor, installed a new wiring harness, and learned about rust repair, Lucas electrics, and level-arm shocks.
Drove it as my High School car from 77-79. Was a better investment than my 84 3.2 (percentage wise), but with considerably less power and performance.
Bought for $1200, maybe another $1500 in rebuild, and later sold it for $12,500.