The '70-71 parts book lists the following for Challenger and Barracuda hood hinges and springs
The spring listings are a little weird; that first spring (-088) lists quantity 1 for Barracuda; it is NOT the pop-up spring so I don't understand the listing. There's also no callout line for a non-fresh-air hood; perhaps that was serviced only as the 'hinge assembly'? Also no lines for '70 only springs so perhaps the -088 spring is for all Barracuda except '71 only fresh air and both year fiberglass? And the -092 is for all Challenger except the fiberglass hoods.
Why Barracuda gets a different spring for normal and fresh air hoods, and Challenger doesn't is interesting; the Challenger hood of any type is probably heavier than the Barracuda due to the extra length, but a fresh air option probably adds the same poundage to a Challenger hood as a Barracuda.
Maybe its the proportional difference; the added weight on the Barracuda hood necessitated a (presumably) stronger spring, where it wasn't enough to require an even stronger one on the Challenger. (Challengers after all are stronger than the fishmobiles ; )
Hinge, 1970 Barracuda and Challenger 2945842/3
Hinge, 1971 Barracuda and Challenger 3548890/1
Hinge Assy. 1971 Barracuda and Challenger 3582518/9
Spring, Barracuda 3586088
Spring, 1971 Barracuda with fresh air 3586092
Spring, Challenger 3586092
(also Belvedere/Charger/Satellite/Coronet w/Fresh air)
Spring, Barracuda, with fresh air, fiberglass hood 3586215
Spring, Challenger, with fresh air, fiberglass 3586214