The fellow that rebuilt my tranny says that parts of the clutches that failed could be in both and I should flush them.

How do you flush the cooler?

Filling it up and blowing out with compressed air a couple of times?

For the convertor he is recommending rising out with Varsol and spinning the convertor around a few dozen times and repeating with fluid and again with varsol.

Is this right?

you can get a can of cooler flush that hooks up to the cooler lines or if you have an old electric fuel pump you can use it to run some mineral spirits through them and then blow them out with air. As far as the converter it is a sealed unit and you cant really get them flushed very good without them being cut open and cleaned.

As said a can of cooler flush for it and my old shop had a machine to power flush converters but EPA regs put an end to that

should I not trust the convertor? I do have another I could use.

Always use a new TQ with a new trans unless you know it's spotless. If you want to flush the system go to Walmart and get 2 gal of cheap Dex Merc, unhook your return line from the cooler, get a piece of hose that will reach a drain pan, have someone start the car. IN PARK,( or Neutral on MOPARS) let the fluid run into pan until it spits, shut off engine, refill, start, purge into pan, repeat, until fluid is clean, run till it spits, drop pan, change filter, refill. I just did it to my Olds last night. It will flush out everything. If you want to get REAL anal, raise the back of car and run through the gears. Good Luck.

a stock mopar valve body does not circulate fluid in park that's why you check the fluid in nuet.