1987 300TD: 2nd-3rd transmission slip ?

My 1987 300TD transmission has just started slipping when it shifts from 2nd to 3rd gear. As it shifts, the engine revs a bit and then it catches on and is fine. If I release gas while the shift is
happening, it seems to work better.
Is this just going to get worse until a transmission job ?
Are there any magic vacuum hoses to unclog and have this get better ?
Any ideas this group may have would be appreciated.
-- THanks, Andrewe
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You don't say how many miles this box has traveled - probably 150K or more.
Suggest you eliminate the most obvious possibility - old fluid. Do a "transmission service" drain the fluid, including the fluid in the torque converter and replace the transmission's filter. This often postpones the dreaded "day of reckoning".
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Chances are you only need a vacuum modulator on your tranny! Try this: At the front of your engine there is a vacuum pump (it has to be changed by 200k miles to prevent very costly damage), at the top there is a vacuum hose which goes into an "H" fitting. Remove the vacuum lines from the LEFT side of the fitting, and plug the holes. This will bypass the plumbing that was designed for the trap oxidizer which was replaced on recall. Your tranny should shift much better and your car should run better. At this time, 17 year-old 124's have rear, upper strut link failure. MB has upgraded the arm and bolt to a more heavy duty part. This arm bears the brunt of the weight when turning a corner. Front swaybar bushings have been upgraded to a denser, synthetic part. P.

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