When my rear was rebuilt after the accident, I had the shop install 3.73 gears, replacing the stock 3.23 ratio. I followed the advice of the FAQ of www.thirdgen.org and the Tech Central article Speedometer Gear Swap for 700R4 Transmissions and ran into a couple of small problems. One major problem is that all of the part numbers given in the FAQ are for the Electronic Speedo cars. If you have a mechanical speedo cable (like mine) you'll have to check with the dealer to get the correct part numbers for your trans. The other "problem" I had was I was blindly following the Tech Article for changing speedo gears, and had removed my drive shaft before realizing that I only needed to change my DRIVEN gear, not the DRIVE gear. The major portion of the work is if you have to change your DRIVE gear, the DRIVEN gear change is trivial.. I spent an extra hour setting up the proper jacking of the car, removing the drive shaft, etc. and then just had to reassemble it all again... YMMV..

Click on any image below for an enlargement (~500K) image.

Proper jacking for working on speedo gears. Rear wheels must be free to spin because you normally have to rotate drive shaft to remove it from differential. Jack is kept under car for safety, making contact but not load bearing.

WRONG parts ordered from FAQ. The gray (15 tooth) DRIVE gear is correct, the blue (45 tooth) DRIVEN gear is for an electronic speedo cable..

Correct parts. The sleeve is needed if going to a higher "range" (tooth count) of DRIVEN gears.

My stock sleeve accepted gears with 34-39 teeth. This new sleeve accepts gears with 40-45 teeth (The new sleeve doesn't come with a O-ring seal. If your stock one is old/damaaged, remember to get a new one. Mine was ok so I reused it.)

The 44 tooth (Dk Gray) gear for the non-electronic speedo cable. (has a long plastic shaft that the cable fits into). This is the correct ratio (15/44) for my 3.73 gears, but I currently have rear tires that are 5% smaller and work out to a 46 tooth DRIVEN gear. I picked up the 44 in case I go back to stock diameter wheels at some point.

The 45 tooth (Lt Blue) gear for the non-electronic speedo cable. (has a long plastic shaft that the cable fits into). This is the largest (tooth count) gear that is made, so I'm using it instead of the proper 46 tooth count gear that I would need for the best speedo reading for my small tires and 3.73 rear gears.

Speedo cable (non-electronic) hookup into trans

DRIVE gear inside of trans with DRIVEN gear&sleeve removed from trans.

DRIVE gear inside of trans with DRIVEN gear&sleeve removed from trans.

Stock Blue DRIVEN gear (38 tooth) &sleeve removed from trans. (3.23 rear)

Stock Blue DRIVEN gear (38 tooth) &sleeve removed from trans. (seperated) (3.23 rear)