When swapping speedometers do you have to change the little meshed gear inside the transmission tail housing if you go from an 85 mph to 140 mph. I just put in a new Tranny and had to change it since the 700 R4 was out of a caprice with a diff. trans. but now I want the bigger speedo since I bury the 85 twice a day. thanx.

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86 Firebird, 305 4bbl, Flowmaster 80 series.

Sound System: Pioneer Head Unit, 2 Ground Zero 12" Nuclear Series Subs, Rockford Fosgate wiring, Crappy Amp untill July

Work to be done in July: New Engine (383 or bigger) New worked 700R4, power Sunroof, Trans Am Body Kit, Ram Air II hood, Rims, Tires, 1.5" lowering springs, and re-done interior...I want yellow and black but the 4th gen conversions look tempting, oh yeah painting it Yellow also

 

I didn't have any trouble with it, I swapped the entire speedo and it reads perfect. This is an a camaro, but should be the same with a firebird