ticking in engine HELP!

[Andrew <lynx@domain.elided>]

Hey guys,
   The 345 V-8 in my '69 1200 has made a weird sound lately. I guess I would call it a ticking.  When I first start it the noise is really noticable. From what I can tell it comes from the inside the oil pan. It sounds like a lifter tick, but it's not from the lifters. If it warms up a little and you hold it at about 1000rpm the loudness of the tick goes away.  Once fully warmed up the tick goes away even at idle. But the is still a very slight high speed tick inside the oil pan which has always done that. Never enough to make me worry until now. It's weird that if you give it gas instead of speeding up, it really just goes away. 
  Any ideas ????  It's kinda got me worried these last two times.
Thanks a lot,
Andrew Thomas
'69 1200 4X4