Note screaming chicken decal on the hood (a $55 option that year.) They were still fairly small, but by the end of the decade they'd have eaten the whole hood.
The "455" on the hood scoop lets us know it has the base engine for the Trans Am package, the 250bhp L75, rather than the optional 290-horse Super Duty LS2, which would have added another $550* to the MSRP and an "SD-" prefix to the decal on the shaker scoop. '73 was the first year that emissions regs began taking a really noticeable bite out of the Trans Am's output, with most previous reductions being a result of shifting from SAE Gross to SAE Net power measurement and some fiddling with numbers in the marketing department.
*$550 was a steep option in 1973, when $2500 would buy you a whole Pontiac Ventura coupe.
