Google search for 1989 Pontiac Trans Am overall length yields:
https://www.conceptcarz.com/s2344/pontiac-firebird.aspx
Length : 188.1 in | 4778 mm.
Wheelbase : 101.0 in | 2565 mm.
Had to do the same with my GTO to make sure it would fit. New home garage sizes are pathetic.
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1970 GTO (Granada Gold) - 400 / TH400