Need Help Replaced the K1 kit on my 300 SD 1985 it work good for about 1 da,y today I took the car for a spin and found the trans don’t up shift to 3-4 it stays on 2 even if I go to 4500 rpm.
Checked the vacuum lines all are ok.
Did the K1 kit was not properly done?
Am I looking to a trans rebuild or may be something easy?
Any suggestions?.

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2000 430 ML
2005 S500
87 300 D
61 300 restoring