So a couple of days ago I was getting on the freeway, and punched it while it was in 3rd gear. My aod downshifted to 2nd and the motor revved to 4500rpm. Ever since then the old 302 started ticking on the passenger side. Under load, it ticks from about 1700-2000rpm and then 2500-3000rpm, but is fine at other speeds. Once i let off the gas, it quiets down. I get a faint tick at the same rpms if i rev it in park. I recently put on headers but i checked for leaks with a garden hose to my ear and found nothing. Does this sound like a lifter or something more serious? its an 89 302

 

I changed the header gasket and the ticking stopped.