Re: New to the nation with 4r100 problems
A stock trans will hold up just fine with a stock engine.
To make the new trans live, scrap the air to oil cooler that's on the truck. It's contaminated and can't be cleaned well enough to reuse it. Replace it with a cooler from a 6.0L truck. It will bolt to the same mounts. You'll need two 3/8" - 1/2" adapters to connect the lines. Any hardware store will have these.
If you have a radiator cooler it probably can be flushed. Most of these are simply a coiled tube. If it is a small stacked plate cooler it needs to be replaced.
Former Ford Automatic Transmission Engineer
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