well i finally got the truck up on stands right side and let it run in gear to find this clicking sound
it would only appear at a constant crusing speed
found the emission relay for the evap purge system(i guess) was the problem
my question is- is this common do all these relays click that loud(like a stone in the tire)
i dont want to replace it if the new one is going to do the same
i'll wrap it in insulation.lol

1991 b2600i

 

There are a few types of relays that will make a click, usually cheaper ones that are intermittent, like for your wipers and flashers. Most relays shouldn't make any noise at all.

The noise on yours was caused by the contacts arcing.