My Jimmy has 33 inch tires with the stock 3.54 gears. Is there any way to change the speedometer gear to correct the speedo? GM doesn't sell the gears anymore. Anything aftermarket? I got a quote from a Speedo shop to recalibrate the speedometer for $165 but would like to do something different if possible in case I re-ratio it in the future.

 

gearing it differently won't mess with the speedo its only your tires that'll mess with it. now the gearing will change how your truck shifts but not how the speedometer reads. you should probably run at least 3.73's with 33" tires you're gonna have some loss of power with the stock gearing. check 4wheelparts.com they have a lot of gearing solutions for all trucks

 

Is your speedometer cable gear driven? If so I would change the little plastic gears instead of paying to have it recalibrated.

 

88 should still be cable driven. Luck has it GM has decided to quit making the gears for our speedos and the aftermarket hasn't picked them up. Good luck finding a set

 

Gearing will change the speedo. Since the axle will spin at a different speed ratio with the driveshaft.

 

hmmmmmm new gearing hm.........ineed to correct my speedo too...

 

Your original tires were likely 205/75R15 which are ~27" diameter tires. With 33" tires, your speedo is now reading ~22% too slow.

You can get a ratio box which will alter the speedo cable speed. Check out THIS PAGE.

Re-gearing to 4.10's would bring you back to just 6% low. 4.31's would be perfect, but the next step from 4.11's is 4.56's which would cause it to read too fast by ~7%.