Planning on changing the transfer case vacuum switch and the actuator cable to front differential. Should I go to the dealer and buy the GM parts or would the Dorman ones sold at the auto stores be ok?

 

Usually Dorman is okay. However, You might want to call a dealer and see how much it costs, you might be surprised. I have ordered parts from chevy because they don't cost much more than something from your local parts store. When I ordered my defroster vent it was cheaper from the dealer than eBay.

 

In general, go with the GM / AC Delco part. The GM dealer is not the only source for these parts. gmdirect.com, Advance Auto Parts and Rock Auto and there are many others that carry AC Delco at better than the dealer price. However, if you need to get your truck back on the road and the parts guy has only Dorman in stock, you may have to go with that. I just bought a Dorman vacuum actuator switch for 18.39 plus tax and put it on my 2003. It fits and works fine. It was a pain to re install. You have to press the switch in while you are turning the switch to engage the threads. This is to compress the spring loaded plunger enough to catch the threads. Be careful not to cross thread. I could only get my left hand in the tight area above the transfer case. Be sure to clean the area around the threaded hole before you remove the old switch. Butcher, after re reading your post, you may be talking about the bellows/ vacuum switch under the battery tray that is connected directly to the actuator cable. I am talking about the small switch mounted on the top of the transfer case . Sorry for any confusion.

 

It is the switch on top of the transfer case.

 

Good, I was talking about replacing the switch on the top of the transfer case. Go to my thread about my 2003 Blazer and on Page 3 there are two You Tube video's that you will want to watch before you tackle the project of the switch. I warn you as the You tube guy's say, it is hard to access the switch. The wrench needed is a 7/8" and those are usually long. You need the shortest 7/8" wrench ---or the metric equivalent --- you can find. 7/8" = 22.25 mm. I guess we are saying use a 23 mm wrench. Stubby is the key word! Here is my post, see page 3. Dorman part 49315 for '03.
4WD-- '03 wheel won't spin freely when off the ground.

 

I forgot to say that the Dorman part doesn't come with a new 'O' ring. Be sure to have a new O ring before you start removing the old vac. actuator switch. GM part no. for this 'O' ring is 14048044 but you can get an equivalent at NAPA.

 

I actually ended up ordering the GM parts online. Should being here Tues or Weds then I can get them installed. Also going to redo the vacuum lines as they are showing their age.

 

Butcher, please let me know if the GM part comes with an 'O' ring. I installed mine without an 'O' ring because my only vehicle was out of commision because I was working on it. I also would like to hear how the vacuum leak 'search and repair hoses' comes out. That is a very worthwhile job, but one I have always found hard to do. Please note that the video's I listed on my separate post on the 2nd Gen. section 4WD--03 wheel spin....have a couple of Mark Jenkin's You Tube vid's which have at the end a list of 'how to find vacuum leaks' which you may find helpful. Keep us posted.

 

Jimspahr, will let you know.

 

Jimspahr,
Just received my parts and the vacuum switch does not have a o-ring with it. I totally redid my A/C this summer and have a ton of o-rings I bought when doing that job. Sure I have one that will fit.