Does anybody have a copy of the gm service manual from helm inc? If so, is it the same service manual the dealers use? Does it list all the part numbers? Does it list all the engine codes? Does it lost all the chassis codes? Does it offer solutions to the codes?

I have also seen service manuals on eBay in the 3000 page range. Is this the same as the helm manual?

If you have both or have seen both versions (if they are different), would you recommend one over the other? Why?