4R44E to 5R55E

[dranger21]

I have a 99 3.0 4x4 with a 4R44E transmission that may need to be replaced. The radiator blew a whole in the transmission cooler so had antifreeze in my tranny which obviously isnt supposed to be there. SO.. I was thinking if i replace it I might just put a 5R55E in it. Will the 5R55E bolt right up without and major modifications and will this give me any better gas mileage or power. I do a lot of highway driving and I was thinking gas milage may be a bit better with a the 5 speed auto but i guess that depends on the 5th gear ratio. Anyone know the answer to this or think this is a good idea/bad idea? any input would be appreciated.Thanks in advance

 

[Bent Bolt]

Swapping a 5R in place of a 4R will not get you a 5 speed auto, the extra gear is in the PCM programing.

 

[locovaca]

The 5th "gear" comes between 1st and 2nd on the 4 speed, so having it won't help your highway driving anyway. 4th/"5th" have the same final ratios. So unless you puttering around the interstate between 1st and 2nd gear you won't see a change.

http://www.therangerstation.com/tech_library/AutoTrans.html

 

[dranger21]

thanks. for some reason i didnt see that in the library. im blind i guess