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Transmission interchangeability 99 gtp

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Scottycamaroz28

New member
My transmission needs to be rebuilt or replaced. For price purposes I am going to get a used one. My issue I have is after seaching all over the forum is interchangeability between years with different coolant fittings, valve bodies and whatever else. My car is a 99 built in November 98 so it's an early 99 model. I want a direct bolt in without dealing with swapping out lines. I know the 97 and 03 won't work. I have found 99 trannys near me but they are overpriced and higher miles and when I search for 98 model years I get lower mileage units and better prices. I need to know exactly what years and SC models of cars will be a direct bolt in without any other issues with coolant lines or wiring.
 


if the transmission is a 4t65HD it should be fine. i know the 97 is a different model trans, but im not sure why a 2003 trans wouldnt work. im no expert on the topic but i would think the 4t65HD should from any 98-03 should work.
 
You must buy a 97-02 4T65E HD trans for it to be a direct bolt in. The change is that in 2000 to 2002 the trans cooler lines have a different fitting, they went to a snap in/quick connect, buts its nothing 10 minutes of your time can't change to swap them around.


You cant use an 2003 because the valve body and the way the PCM controls the trans is different.

You cant use a regular 4T65E from a GT because the gearing is different.

And to clear things up, the 97 SE and GT were the only years to come with the 4T60E which is vacuum controlled and is a year only thing. The 97 GTP still came with the 4T65E HD thats in all 97-02 cars.
 
Fivefingerdeathpunch said:
You must buy a 97-02 4T65E HD trans for it to be a direct bolt in. The change is that in 2000 to 2002 the trans cooler lines have a different fitting, they went to a snap in/quick connect, buts its nothing 10 minutes of your time can't change to swap them around.


You cant use an 2003 because the valve body and the way the PCM controls the trans is different.

You cant use a regular 4T65E from a GT because the gearing is different.

And to clear things up, the 97 SE and GT were the only years to come with the 4T60E which is vacuum controlled and is a year only thing. The 97 GTP still came with the 4T65E HD thats in all 97-02 cars.
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interesting, thanks for clearing things up
 
I found a 99 park ave ultra with 3.8 SC engine and good trans. Am I not mistaken that this trans is the same as mine and will bolt in no prob?
 
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The rear mount is different. Not sure if it's a direct bolt on. I have a trans laying in my garage with 20,000 miles on it but not sure i want to sell it.
 
I'm kinda thinking it wont.

The quick search I did says all park ave ultra got 3.05 gearing compared to other L67 cars that got 2.93's.

Which seems odd to me.
 
ehhh..... the transmission in my 99 GTP is outta a buick park ave I think... I wanna say I had to switch a mount but that was it... not sure on the gearing...
 


Scottycamaroz28 said:
Ok thanks for the info guys. And Dsmuts would you sell the trans you have and how much and where are you located?
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I'm located in coldwater, oh. If i sold it i'd have to get $500 out of it. If it stays sitting on the shelf i'm fine with it but if it sold i wouldn't be to sad lol
 
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