Brake rod spring,do i need it

Changing to a dual m/c for a 67 coronet onto my 66 to do away with the single pot m/c. the 67 seems to have an internal return spring so i was thinking i could use the brake rod and boot without the external spring. is this correct?

I changed my 66 ,had single master with manual drums, over to a dual MC, with 76 a body front discs. I really don't remember an external type spring to begin with but It was a while back when I did it. Anyway I took a look and FWIW I don't see anything up there but the dust boot, works fine though. My GTX is power drum, I believe the PB cars have an assist spring internal from the booster to the pedal rod, never had it apart though.