I have a 07 4x4 f150 5.4 with a bad 4r75, I have a 04 4r70 out of a 4x4 f150 4.6. Can I put the 70 in the 2007 5.4?

 

The 4R75 was a heavier duty trans and the 70 might not deliver the same length of service you might be accustomed to.

 

The 4R70W can handle the horse power and torque of your engine.. The 4R75W is the model that replaced the 4R70W transmission around the mid 2000's with some improvements. In fact, they both use the same oil pan. The torque handling specs are very similiar for the two models. Both are rated to handle up to 500 horse power.

 

We have to be careful here and with that , the word "HANDLE" can mean different things.
It would be a wise move to learn the differences and the conditions the trans will be subject to .
They made some of the changes for good reasons and depending on what longevity you desire gets into the picture.

 

The 4R70W was used with the V-8 engines to 2004 or 05 and going back into the 90's.. The 4R75W was not even a twinkle in the eye of the automotive engineers during the late 1990's and early 2000's. It's time to stop splitting hairs and playing word games.

 

If it was my $$$ I would want the most I could get for what I spend.

There are many explanations to explain why the changes were made and a trip to a trans shop would be a worthwhile trip to consider

That way you would be getting the benefit of their experience too.

 

He already has the 4R70W so that expense for a transmission would equal zero. I would use the 4R70W myself if I were in his shoes, already having a suitable transmission. Also, anyone familiar would know the transmission model he has is a solid performer. They were used extensively in law enforcement vehicles and by many others who accrued hundreds of thousands of miles on them. If rear drive vehicles were still being made, the 4R75W would likely have been replaced with another model anyway. Doesn't mean a new model is better either. It's all about money.
Anyone who is familiar with the auto industry would know there are refinements over time made to transmissions, engines and all kinds of components. Could be smoother shifts, better fuel economy, who knows. Those changes do not mean the previous model was defective.

 

What is the original problem with the 4R75 ?

 

If,,,,,,,,,,,,you attempt to install an older 4R70 where a 4R75 was originally installed on the 2007, you could run into some addl problems like you would need to also change the PCM, there is an addl sensor used on the 75 that the 70 may not have provision for, and that would be enough for me to step back and get more accurate info.

Can't tell you what you should do, but can suggest caution and do some very detailed checking before you wind up with an open can of worms.

 

4R70 transmission may not be able to handle the increased power and torque of the 5.4L engine, which could lead to premature failure of the transmission.