The O rings will likely fix the problem.

I have seen situations where if the bracket holding the dipstick tube to the engine is tweaked a bit it will put the tube in a bind (more pressure on one side of the tube than the other) and cause a leak.

I'd advise strongly against over-filling the transmission. Transmission fluid has a pretty good expansion rate. Too much fluid especially if you have a long hard pull, like going up a long steep hill, can cause an overfull transmission to blow excess fluid out the vent. TH400s were pretty notorious for this.



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