i got a 99 gmc sierra is there a better computer to go to

 

you can load the 99 computer with an 02 OS or just get an 02 PCM and have the vin changed.

 

Yessiree...I have an 02 PCM and it's a much better OS than the 99 which is prone to false knock among other things. Back when I got my 02 PCM we were still in the research phase, and a couple other guys were experiencing problems, and shortly after so did I (cam swap brought out the 99 PCM's demons). Also, 99 has smaller injectors than 00 and up...I believe that 99's are either 19 or 21 lb. vs. 24.7 for 00-07. So if you swap PCM's, you will either have to swap injectors, or copy the 99 injector values into your 01-02 PCM

 

how hard is it to change to the 02 pcm an what has to be change plug wise

 

It's a direct bolt-in, piece of cake...the PCM is under the black plastic cover by the battery. Oh wait...I almost forgot. The 99 alternator isn't directly compatible with an 02 PCM, I had to replace my alternator with a newer one, get a different electrical connector to the alternator, and run a wire from the alternator to the PCM, as the newer charging system uses a sort of PCM duty cycle. Glad that I remembered that, it's been a long time. By the time you're done buying a used PCM and alternator, and getting a crank variation relearn done, you could have bought a custom tune for your current PCM from BlackBear, and request to Justin that he flashes in an 02 operating system, if it isn't something that he does already. He can modify the PCM without needing the external mods such as an alternator or 00+ injectors to match the 02 PCM's injector values.

 

Even quicker rather than waiting for a response, get it done locally.

So you can't swap a DR44 onto a 99 directly as long as it keeps the 4 pin connector? I know there was a difference on the 05's with the 2 pin connector, but thought these were plug and play.

As far as the 02 PCM - is there a specific serial number/part number to watch for? Seems like there's some variance with the PCM's and different part numbers. When boneyard picking, how do you know which one it is?

Is there anything that's good on a 99? Seems like just about everything was revised/replaced in 2000