305 intermittent lifter noise

[rigfixer]

Have an 89 gmc pick up 305 with an intermittent lifter noise. Well you can hear it always if you really listen, i mean really listen. Every now and again one just starts really snappin' aloud. Any easy way to find out which one and if the cam lobe is junk. Was gonna put a dial indicator on each and measure lift, that sounds like work. Thinking about just changing the cam and lifters but thats cash, the truck is old. Possible stickin lifter?? Heard about running tranny oil in engine for a bit to help loosen up carbon?? Any Ideas would be appreciated and if ya need a hand with any big diesels give me a shout would be glad to help, thanks.