Need to know what I need for this.

Hear it harder to do then just taken the tail shaft off like on a auto and its on a truck so I have to take the transfercase off to.

 

there is no accurate speedo ratio for 4.10's

 

i will tell you this its easier to remove the tranny from the car to take the tailshaft off,you need to remove the roll pin from the shift rod,loosen the bolts to tailshaft and slide back it should take 2-4 hours to do.....

 

Well I have 285/75/16R tires on the truck could I get close with these bigger tires.

Is there a manual I could get or should I just talk to my friendly GM service man.

 

Prolly a 15/39 or a 17/45 may work, but you should checking using the match in this thread, also found in the tech articles.

https://www.thirdgen.org/techbb2/sho...t=speedo+gears

 

Yes there is. I have it in my car right now, and it's up for grabs in the classifieds. Look it up, still for sale.

 

Here check this out.

http://sethirdgen.org/t5speedo.htm

 

Hmmm, interesting. Maybe it came off of a truck with 4.10's. Do you know what got that gear? On the math issue though, I would make sure that is the right combo from gm before you put in on because the math the online calculators use is simply wrong and definitely does not coincide with what gm put in their vehicles.

 

Wouldn't the speedo drive be on the rear of the transfer case on a 4WD? It was on my 78 Blazer. They would probably use special gears as well.

 

Didn't come off of a truck or anything, I worked at a pontiac dealership at the time, and spend 25 mins with the parts guys lookin through gears for thirdgens, and finally found a special order 29 tooth gear to match a 7 tooth, which by doing the math works out to 4.14, and with my 16" tire it's right on the money.

 

are you sure on that I never even looked on the tranny or any thing to see where the speed sensor or cable is I just assumed
it was on the tranny
thanks for the tip. Petes 84Z28

I'll have to look.

 

Fairly sure, because the hi/lo range in the transfer case would throw off the speedo if it were getting it's reading on the trans.