Brake problem?

[71400lb]

I have a 71 C/20 Long bed 2 wheel drive. The previous owner installed a Crane Cams back-up canister booster for the breaks...told me in case the main brakes fail, the back-up system will get you home.

Right now when I press the brake pedal as hard as I can to stop, the truck slows down quickly but the tires don't lock up.

My question is, shouldn't my breaks lock up the tires when I floor the brake pedal?

Is it normal the way the truck stops or do you think there's a problem?

Also could it be that the main brakes are not working and I'm only stopping with the Crane Cams back-up canister?


Thanks all,
Rick

1971 Cheyenne 3/4 Ton Long Bed
400/400
3.73/open H052 10-bolt