I have a 97 blazer that when driving in 2wd it will sound like front pumpkin gears are growling, if you put it in 4wd the sound will stop for awhile. could it be vacuum or something else?

 

first thing I would do is get under there and pull the plug and check the level, it should be just below the hole. If I take my truck in for an oil change I have the tech check both differentials and transfer case everytime

 

it sounds like a problem i had, but when my actuator went, 4wd just wouldnt work....no noise. wow i have a ****ty memory. i cant remember what the problem was, if i remember ill post again. sorry bud. i dont think it was too expensive tho.