I have a 2002 S10 Blazer (3 Button).It shifts into 4WD Hi fine but when I go to put it back into 2 wheel there is a delay, sometime several miles and the a loud bang like someone hit the bottom of the vehicle with a hammer. I have changed out the vacuum front axle actuator (under the battery) and I am in the process of changing the Front Axle Actuator Solenoid Valve, which I currently can't locate on the vehicle (it's not on the firewall).

Am I replacing the right items and is there anything else that I need to look at?

What about a vacuum switch on the transfer case? (Not sure if thats what it's called)

 

how many times are you going to ask the same question? find the thread that you started it in and keep it on there.

https://blazerforum.com/forum/2nd-ge...ocation-84200/

 

You can't locate it because you don't have one.
It's the 4 button version that uses the firewall mounted solenoid, not the 3 button ones.

I'm not a mechanic, but it sounds like it's your shift motor acting up.