Have you checked your transfer case for the missing transmission fluid? A bad front seal on the TC can allow fluid to seep in from the trans. I would image 4 quarts would have it blowing out the vent, but it may have been low in the first place.

 

No I havent,but I will. But I have had to fill it up 3 times . So it would be like 12 quarts. I some how think it's getting mixed in with the oil. Because that is gaining the same amount the tranny is loading. Just can't figure out how though.

 

Interesting. Isn’t this kinda like those Sherlock holmes mysteries where when you’ve eliminated what it’s not it has to be what’s left even if improbable?
If there’s not oil in the coolant & coolant in the oil then somebody has to have plumbed something wrong and sold it to you.
The only other place the two come in close proximity would be at rear oil seal which I’d list as an impossibility as the path.

You said there “appears to be a small oil cooler .. to oil filter” . Is this standard or did someone add that on? I don’t know what options there are for your year/model but I have 93 with towing package/heavy duty cooling and both oil and tranny lines are in radiator as others have said.

Do both lines from the transmission go to top/bottom of the same side of the radiator?
On on opposite side from where the tranny lines go into radiator ( memory is that’s the passenger side if it’s like the 93 year) do you have two other lines going into the radiator manifold? If so, where they go to/from? And where do the lines which go to/from the small oil cooler go?

 

so your rad doesnt have an engine oil cooler?

 

Mine does, it’s in the radiator manifold on the drivers side. I don’t have a separate oil cooler.
Maybe I didn’t understand but when Jake said “what appears to be a pretty small tranny cooler” with the oil lines going to it, I thought he was saying it was a separate oil cooler. If so and someone added something there would be potential for a screw up. Like tranny lines into bottom of radiator on both sides and oil lines into top on both sides - in which case the trans would probably push fluid into oil pan.
If not - then I have no ideas!

 

yes both lines from tranny go to passenger side of radiator. Them are the only 2 lines that do. The pic is of the small cooler that the 2 lines coming off the motor where the oil filter screws in at go.

 

No it is a separate cooler.

 

I don't have any knowledge on various arrangements in different years but it sure looks like OEM with that formed bracket.
So, on driver's side of radiator there are not any lines into the manifold? the only two into radiator are from tranny on passenger side. Just wanting to confirm that the oil cooler is completely separate and not an additional cooler to one in radiator also. I've not seen this kind of set up before.

If zero possibility to mix oil in radiator or cooler - then perhaps it is something like a vacuum line like Irish mentions and you have a transmission which does have a vacuum modulator? I don't know the various transmissions well but this link will help identify what you have Chevrolet Chevy Transmission Identification and Decoding
You might also look on intake manifold for vacuum lines which run towards transmission and if easy, disconnect the line and see if it's oily inside.

 

Jake has never really said what drivetrain he has, I think we all assumed it was 700r4 trans, but a 89 k2500 or 3500 would have a th400 with a vacuum modulator.

I think your on the right track thinking vacuum. Should be easy to pull the line of the module and see if fluid drips out.

 

I just went out and checked, you are correct and it is a th400 with a vacuum modulator. . Going out to see if fluid is in the line now.