Had the stock 42 re transmission rebuilt in 98 Grand Cherokee with a new torque converter and transmission go shift kit. The transmission shifts much better than the stock unit did however, around 70 mph down shifting from 4th gear with the converter locked to 3rd gear a buzzing/ whining noise. The fluid is good it holds gear well and everything works better than stock short of the noise. Don’t think it is linkage related.

Anyone had an issue like this