305 v6 rocker bolts

[wc63]

can anyone tell me if the gmc 305 v6 rocker bolts are pressed in or bolted on? i remember taking the valve covers off a few months ago to adjust the the lifters and the nut a needed to tighten was gone. I think it broke cause i dont remember seeing a thread. i cant tell you how its still functioning, but i put the valve cover back on and drove it home. been driving it in and out of the garage the last few months. im getting tired of listening to the knocking sound and now i have a place to work on it (i was at a friends house the first time). i figure if its a bolt on, i can fix it. if its pressed in imma have a considerably large headache. any info is appreciated