4R100 vs 5R55

[Number4]

I see that the Navigator came with the 4R100 for the years 1998-2002. In 2003 they switched to some ZF Friedrichshafen AG 6 speed transmission, Which was used up to 2007 when they went to a 6R80.
A general question, which would be more of an opinion request I suppose, is why did the Explorers not use the 4R100 with the V8's?

The 5R55 family seems to be nothing but problems. I suppose the easy answer could be weight driven as well as scoped towing/pushing/pulling needed due to GVW differences.

Both have overdrive, though I suppose the 5R55 should get better gas mileage at freeway speed, which would help when it comes to the EPA and stickering these Explorers.

Could 4R100 be put in place of a 5R55? Let's presume one was to put a 5.4l into an Explorer, having in hand the PCM and the 4R100.
I realize that the Cluster is also calibrated to the PCM, so some work or swapping of clusters may be required.

Would the driveline have to be fab’d?

I've not been able to locate any size dimensions for the 4R100 so far. Curious if anyone has any info on why the 4R100 wasn't used.
Hopefully I didn't ramble too much and yes, I'm dabbling in a world for which I have no prior experience. :scratch:

 

[transman304]

My thought on this would be 5 speed vs 4 speed first of all. 4R100 have their share of problems also. Weight and size would be a factor also. Parts prices for hard parts for 4R100 are much higher than the 5R55S/W. Mods to drive line I don't know. The gear ratios of a 4R100 may not be best for mpg and drive ratios on Explores. Just some things that come to mind. An OLD mind at that! LOL

 

[Number4]

So after some searching (using different search terms? Don't know) I've found that the Mustang owners have been swapping the 4r70 and 4r100 in and their 5r55's out.

The 5r55 holds up to 500 rear wheel horse power while the 4r70/100 handles 800-1000 stock.

The 4r70/100 has been made to fit with some tunnel modifications with a hammer.

Not that it's a direct swap. The driveline needs to be modified, but that's only $150 at most, vs needing a new torque converter at $900 and figuring out a flex plate.

I'm going to try and pull the engine with trans and drop them in together, what I still need to figure out is if the trans mounts are in the same location.