Both.
If they make it for my vehicle I buy it. They both seem to supplement each other frequently.

Neither make one for my Expedition yet.
I bought the factory manual in electronic form. Much more of a PITA than paper.

If you have a public library check the online databases they have available. Many have repair manuals available online.

Step 1: Unhook the battery connections.
Step 2: Remove the engine.
Step 3: Install new engine.
Step 4: Reconnect battery.

Thanks fellas. I guess the search starts for a OEM manual.

Helm makes the good ones but they are pricey (http://www.helminc.com/helm/search_service_owner.asp?Style=helm&class%5F2=GMC). eBay uasually sells copies of the factory manuals on cd for much less.

quote:

I bought the factory manual in electronic form. Much more of a PITA than paper

At first I felt the same way. I had to get the electronic form for my 03 Grand Cherokee. After I got used to navigating it though I now prefer it. Instead of having to page through a huge manual with greasy fingers now I just print out the pages I need, highlight the important stuff (torques, special notes, etc) for the procedure I am doing and that is my "working copy" that I don't mind getting all messed up.

I am still waiting for the www to crash, so for important information I have actual manuals. Using the web then, I ordered a factory manual for my ‘95 Dodge Ram Diesel. 3 books, about 1 1/2” thick for each book.

A German employer of mine used to say, Chilton's are full of Chit.

Factory > Bentley (not available for GMC) > Haynes >> Chilton's