Guy's seriousely... ask yourself if the Camaro would have been built if the Mustang wasn't?
NO!!! the vette was doing fine in sales. But Blue Oval found an untapped market. So GM followed.
Die hards hate the stang! That is ignorance in itself!
Seriousely who in their right mind wouldn't want a Elenor clone or a 60's GT500. ADMIT IT!
Anyway, GM falls behind, but they built a better vehicle with more power, better gas mileage and displacement. Ford was notoriouse for crap wiring!
My 1988 IROC has 200K plus miles on the engine and 189K plus miles on the original Trans. Rebuilt then.
That's on a little'ole 305 TPI. I did the maintenance and that's probably why.

1984 didn't have an SS, or you weren't very descriptive on what SS you owned.
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GM's 5.7L LS1 to the Ford 4.6L. The 4.6 is a Huge Engine, It's heavy, The technology in it is pointless. Cause it get's like 18-20MPG real Miles if you are lucky...ridiculess.
I get 23-26MPG on the Highway out of my Stock 99 Trans Am and it still runs better tracktimes that the new stock GT.
That is engineeing for ya! Ford had its hay days and so did GM. GM just happened to have more and make better decisions.
Point is don't hate! Appreciate each other, respect each other and live together in a competative nature as GM rivals Ford.
GM likes the fact that Ford has the Mustang and all it's other products that it can compete with!