I had 3.42 Gears..and Eaton posi installed last year..and never got around to getting the speedo recalibrated..Thers some places around here that want like 180-200$ I went to summit racing and put in "Speedo" in their search..and it looks like the speedo gears are only like 8-10$ what one would i need.
Stock it i had the 2.73's in there
now i have 3.42/Eaton Posi..and im pretty sure its a 26 spline.
-Cory

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Black 1989 Formula WS6 5.0 TBI
Apperance Mods-Tinted, 93 style Formula Decals, Custom chrome screen in cowl hood, Tinted out side markers. 4th Gen Seats.
Engine Mods-Pulleys, Ram Air, K&N, Hedmen Headers,Flowmaster Exhaust 80 Series 3"
!Cat,!Emissions, 160 Thermo,Rapid Fire Plugs,3.42 Gears, Eaton Posi. *LT1 Cam Waiting To Be Installed*
http://www.geocities.com/liquidfx17/Formula.html?1015872348700
1998 CBR 600 F3 "The Other Toy"

 

If you have a 700r4 the closest you can get is a 45 tooth driven gear. That will probably require a new sleeve, too. The gear is cheap but the sleeve is highway robbery on GM's part. It cost me $94 Canadian

 

TTT

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Black 1989 Formula WS6 5.0 TBI
Apperance Mods-Tinted, 93 style Formula Decals, Custom chrome screen in cowl hood, Tinted out side markers. 4th Gen Seats.
Engine Mods-Pulleys, Ram Air, K&N, Hedmen Headers,Flowmaster Exhaust 80 Series 3"
!Cat,!Emissions, 160 Thermo,Rapid Fire Plugs,3.42 Gears, Eaton Posi. *LT1 Cam Waiting To Be Installed*
http://www.geocities.com/liquidfx17/Formula.html?1015872348700
1998 CBR 600 F3 "The Other Toy"

 

SLP sells the drive and driven gear as a set for about $40. I just ordered and installed a set for my son's 87 IROC and it cost about $37 minus shipping for a 3:73 gear set. They also have 3:42 gear sets.

 

If you've got a 5 speed, you may or may not be in luck. GM discontinued the gear needed for the 3.42 in the T5, but the overwhelming majority of the 2.8 5 speeds out there had the 3.42 gears, so you can pull the drive and driven gears out of one of them in a junk yard.

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The IROC Homepage
View the Restoration of an 85 IROC
Weekend projects aren't.

 

Its a 700r4. So if i go to summits webpage..what am i looking for? What part number and everything..i wanna make sure i get the right one so i dont pull it all apart and have the wrong part.