I did a 3.42 gears search and found 15T PN8642620
41T PN 25513048 for use with 245-50-16 tires

Sweet!!!!

I got it figured out now. I have a 15-tooth drive speedometer gear and so to go from 2.73's to 3.42's and having 245-50-16's, I need a 41-tooth driven gear in the tranny P/N 25513048, correct?

So all I need to buy and install is P/N 25513048 right?

Yeah, I found that info in a 4-27-02 post by fbody dude. The
thread was "speedo gear confusion".

Cool, I just read it.

1 last question though, how do I find out for sure if I have the 15T P/N 8642620 already? I have a 1992 700R4 with the LB9 and 2.73's with 245/50/16's....

Thanks!

Go to the hanlon motorsports T5 speedo page and type in your tires size and gear ratio. Then there will be no guess work in choosing the correct gears for a T5. Not sure about an auto trans though.

http://www.hanlonmotorsports.com/t5speedo.asp

Wait are you guys saying that If i go from 2.73's to 3.42' the part number to make my speedo accurate is:

15T PN8642620

Or is it:
41T PN 25513048

Or what? I have a 700R4.

Im putting in gears soon and this is somthing i forgot about. does my computer care about the right speedo gear thing?

15 teeth on the output shaft /41teeth on driven gear.
I assume these are for transmissions with cable driven
speedometers.