The sixth generation of the Ford Thunderbird is a large personal luxury coupe that was produced by Ford for the 1972 to 1976 model years. A counterpart of the Lincoln Continental Mark IV, this generation of the Thunderbird was the largest ever produced; weighing in at over 5000 lb , they are also the heaviest coupes ever produced by Ford (aside from its Mark IV counterpart).
Mark IV was a Thunderbird that weighed more than 5000 pounds.
It states it was a counterpart and actually weighed more. The system found it hard to correctly determine because of the wordign.
( z1 aircraft-type :name ( z2 name :op "Thunderbird" ) :domain ( z3 aircraft-type :name ( z4 name :op "Mark" :op "IV" ) ) :ARG1-of ( z5 weigh :ARG3 ( z6 more-than :op ( z7 mass-quantity :quant 5000 :unit ( z8 pound ) ) ) ) )