Replace your turn signal switch assembly under the steering wheel. They get worn out, start coming apart and all kinds of weird things happen with the lights. The hazard flasher switch is part of that assembly and if the actuator for the hazards is missing, that would be your problem. The assembly comes out fairly easily once you get the steering wheel out, which can be a royal pain in the keister. You have 2 options. After removing the horn button, remove the nut on the column that holds the wheel and either go to an auto parts store and rent a steering wheel puller, (the easy way) or if you're in a pinch, back the nut about 1/4 inch from the face of the wheel and you can grab the wheel at 9 and 3 O'clock, place your feet under the brake pedal, pull up on the wheel hard enough to lift your butt off the seat and alternate your pulling from right to left and try to wiggle it loose. If that doesn't get it, take a hard wood block or large brass drift, and have a friend put the block or drift against the steering column and smack it with a BFH a few times while you pull hard on the wheel.
NEVER, I repeat, NEVER POUND ON THE STEERING COLUMN DIRECTLY as this will mushroom the end of the shaft and you'll never get the nut back on and in the worst case, never get the steering wheel all the way off.
Once you get the wheel off, remove the screws that hold on the turn signal handle and the screws holding the switch assembly inside the column. Then unplug the wiring harness to the switch under the dash and slide the wiring out. Now take all the tools you just used and head to the wrecking yard and find a similar year Chevy for your replacement. If you're lucky, you might find one in the right year range that someone already got the steering wheel and half your job is already done. Good luck!
Unless of course you've got more money than tools, and you can take it to a mechanic and let him have all the fun.