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Discussion Starter #1
Hello all, I need help. I own a 1998 mustang gt with an automatic transmission. The tranny on my car went bad, I believe I found a replacement but not sure if it will fit. It is from a 2000 mustang gt. can anyone confirm if the tranny from the 2000 is compatible with my 98 mustang??? Please please help
 

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It is but u may have to change the speedometer gear thats on the inside of the trans tailshaft if urs is mechanical I forget when they went to a digital setup... Either way its not hard to do u just have to take the tailshaft housing off and ull see how it comes off then.... Just make sure u use a oil resistant silicon when u seal it back up such as rtv black or grey


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It is a direct bolt in but you will need to install a dallas speedcal to convert the speedometer output from the 99/00 trans to the 96-98 style. I just went through this last year. Send me your tire size and rear gear ratio and ill see about calculating your dipswitch settings for you.

youll also need a new speed sensor for a 99-04 car if this trans does not come with one.

the 99/00 is actually a much better trans btw, ford updated them with carbon fiber blocker rings and a corrected 5th/reverse slider. IMO, the 99/00(and very early 01) cars had the best 5 speeds to come in a Mustang. The t45 is as strong as the 3650 that replaced it in 01, is a single rail shift design so its butter smooth and no teething issues that the 01-04 transmssions had.
 

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Discussion Starter #5
I thought by just swapping out the tail shaft and the speed gear from my car to the 2000 transmission would fix the VSS / OSS issues. If not, where can I purchase a speed cal converter?? Thanks, this is very very useful information. I appreciate the info.
 

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You could do that... but its easier to do the speedcal and then you can easily change your calibration to any gear you want with the simple changing of a few switches. No tune/retune required. You can get the Dallas Speedcal here


https://www.dallasmustang.com/speed-cal-1994-2004-5-speed-cars.html


Other places sell it too, use google.


The formula to get your corrected VSS output that you need for putting a 99-up OSS transmission in a 98-down VSS car is:


REAR tire revolutions per mile multiplied by your rear gear ratio multiplied by 12.


-You get your tire revolutions per mile here:


Tire Size Calculator - Discount Tire Direct


-Gears you should know, if you don't then find out.


-12 is the OSS pulse count of a 99-up trans.


You take the number you get and plug it into the Current Setup VSS pulses Per mile block of the calculator here


Recalibrator & Speedcal Calculator


Do not put any commas in the number or it will not work.


The binary number you get in the extended range switch setting is the dipswitch setting you use. Not hard.
 
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