I've owned this truck since new and I just turned 100K miles. I believe I have the 4R100 transmission. Here lately when I accelerate slowly, my transmission shifts and I hear a chatter, usually from 2nd to 3rd gear, or from 3rd to 4th. When I shift under normal acceleration it shifts fine.

While checking my service records I found that I had the transmission first service at 32K mile, but it didn't indicate whether I changed the filter. With that low of mile I probably didn't, just the fluid change.

Next I had the transmission flushed at 68K miles.

Now I think I am due for another service and I am really confused as to what the proper service to be done. Some say all I need to do is drop the pan and change the filter, then refill with 8 quarts. Others are saying that is not correct and I need to flush the system.

Also, do I have an external filter? Some shops are not aware of an external filter, and neither am I.....but that doesn't mean much either.

Regarding my chatter when shifting, do I need to just add an additive for this issue?

Lastly, if I go with a synthetic fluid I need to do a complete flush? As you can see I'm totally confused.

 

You should change the fluid. Not just what's in the pan, but all the fluid. Here's how. Changing ATF Fluid in a E4OD and 4R100 transmission .: Articles
The internal filter is the only filter the transmission has. It is not a very fine filter and it is good for the life of the transmission. You don't need to change it until the trans is rebuilt.

Do NOT use additives.

You should always do a complete flush with or without going to synthetics. Synthetics are completely compatible with non-synthetics.

 

Here's an update I posted in my other thread:

Kind of got screwed. I took my truck to a shop nearby and had the transmission flushed. They advised they had the equipment necessary to do this job correctly.

They drove my truck to the back of the shop as I waited. After a while I walked back to the service area and I noticed only about 6-7 quarts of transmission fluid sitting on top of the engine bay. I asked the mechanic if the remaining quarts were all that were left to be put in, thinking that they had already used about 10 quarts already. He stated that they were only putting in the 6-7 quarts as that is all they could get out.

I said this truck holds 18 quarts....I thought this was a full flush, not a partial? He advised that they drain all they could from the pan and hook the truck up to their machine and suck out the rest. Something didn't sound right but I was too late to just get them to stop. They had already drained my fluids.

Next time I'll be going to a dealer or a more reputable shop to do the flush correctly for a full system flush.

I will say that the shutter is gone and it does shift better, but they stated they added a anti-shutter additive. What now???