How much horespower?
Depends a lot on what engine yours might have. The 5.0 L V-8 engines had in the area of 125-150 base hp, because of being so strangled by early emission controls. The 2.3L Turbo 4-cylinder (not sure if it was offered yet in 84) had slightly higher HP, but suffered from head gasket and other problems.
Search Ford Thunderbird Questions
Ford Thunderbird Experts
Related Models For Sale
Used Cars For Sale