1968 would be a banner year for Donohue in the Trans-Am series, as he successfully defended his 12 Hours of Sebring victory by partnering with Craig Fisher and driving his Penske Chevrolet Camaro to victory.
1968 sería un ano excepcional para Donohue na serie Trans-Am, xa que defendeu con éxito a vitoria nas 12 horas de Sebring asociándose con Craig Fisher e levando o seu Penske Chevrolet Camaro á vitoria.