Popping rattling noise in front slipping and leaking tranny

There might be some worn parts in the differential. If you have a limited slip differential the clutches will make that noise.

Tranny fluid is low,,,top it up and check fore leaks.,you may need a new axle seal on the tranny

get it fixed.
take it to any mech,.
and id have him find the noise source and cause of leak.
then work from there.
we are blind and deaf there. we can do neither,

for leaks, we clean it prefectly then drive it 10 miles
and find true source
or use the UV dye test.

Pull the valve cover off to check for rocker arm. Could be exhaust leak if more of a popping sound than a rattle.

Remove the transfer case and strip it down,wash it out and replace whatever is worn.
330,000 miles is unrealistic
Your chain is worn and stretched for sure, and rattling and may be cutting into the case.
Don't install another salvage yard unit, unless you can not repair yours. Then strip down whatever you purchase, and go thru it also.

it sound to me that the tranny needs to be resealed that the seals and gaskets are worn. There are many places the tranny fluid can come out of like where the front axles go into the tranny or the front seal or the pan gasket

could be your front lower control arm bushings. they are notorious for failing.

this sounds like a bad clutch throwout bearing in tranny. if it makes a rattling noise then its the bearing. when clutch pedal is pushed in.

If there is another dealer nearby get a second opinion. Repairs these days are very expensive.

If its the main seal gone,you will have to remove the tranny regardless because the main seal is the torq converter seal.Even though it leaks,if its slipping when full of oil chances are your tranny is no good,if it shifts fine its not to late,just keep it full of oil and have the leak fixed.Look under the front of the car when its in park,with the e.brake on and running,look for the leak.If the leak is between the the motor and the tranny its probably the main seal.Check the transmission pan,axle seals and coolant lines for leaks also.Changing the transmission is no small job and should be done by a garage if your not sure how to do it.Hope this helps.