Seems there are a lot of threads about the OBS clusters, what can be done to change them, and what the difference are between them. I've had this on my website for a while but not too many know about it so I'll post everything here. Hopefully this can be made a sticky for the interior forum. I may even do a info faq for the NBS clusters if the interest is there. I will also add any info that may come up that would be a good addition to this info post.
I WILL BE ADDING A TECH FEATURE ON HOW TO SWAP YOUR STOCK ODOMETER INTO ANOTHER CLUSTER YOU WANT TO INSTALL IN YOUR 95+ OBS TRUCK.
Below is a picture of the common 100 mph cluster found in a majority of 95-98/99/00 OBS GM trucks and suv's...
(picture credit to James B.)
Below is a picture of the 120 mph cluster found in 99/00 OBS Escalade, Denali, and Tahoe Limited suv's...
(note the stock clear needles!)(picture credit to James B.)
Last but not least, here is a pic of the 130 mph Special Edition Police Tahoe Cluster..
(picture credit to James B.)
The sweep on the 100 mph cluster and the sweep on the 120 mph cluster are the same. These are interchangeable and require no modifications for proper function and speed readings. However, the Police Cluster is a different story. Here is a pic of the 130 mph sweep versus the 100/120 mph sweep...
(picture credit to James B.)
The Police Cluster can be identified in a few other ways besides the 130 mph sweep. The Police cluster has an identification on the printed circuit and also has a unique circuit board specific to these clusters. No other stock OBS cluster have this and to run this cluster this board requires wiring and calibration. Boosted Z-71 has accomplished this swap and he has informed me of how to do it. You can read his information below.
The cluster is a straight bolt in except in the case of the speedometer function. You'll need to use a Dakota Digital signal modifier to take the stock speed signal and modify it AFTER it went through the ECM and out on its way to the speedo. You'll also have to shield the wires really well at the signal box and all connections or you get some RF interference that causes the speedo needle to jump at times. Some have recommended splicing into the speed sensor wires at the tranny. Do not do this! You talk about messed up shift points, that will give it to you. By modifying the signal after the ECM and on its way out to the speedometer you get transmission shift functions that stay normal and the ALDL scanner data is also correct. All you need is a scan tool and keep adjusting the Dakota Digital box to match your needle to your ground speed on the Scanner. Mine is accurate to within less than 1 mph, from 0-130. The only other way to do this is change the reluctor in the tranny & GM would not sell the police pacage reluctor to me without trading in a similar unit.
(picture credit to James B.)
(picture credit to James B.)
Like I mentioned earlier, the 120 mph clusters found in 99/00 Escalades, Denali's, and Tahoe Limited suv's can be a drop in replacement upgrade for the standard 100 mph clusters found in 95% of OBS GM trucks from 95-98/99/00. As you can see the cluster backlighting is a teal color versus the green backlighting found on the stock cluster. Just another subtle difference along with the clear needles.
Cameron