1984 300d Turbo 138k
Look At The 3,4, Way Conectors If Heat Up They Expand Near The Oil Filter And Leak, On My Diesel It Wold Not Shut Off, Found Vac Leak When Start The Engine Slow Increase In Vacuum And On A Vac Gage Transmission Shifting Improve After 2 Miles Trans Shifting Would Improve Due To The Increase Vac. Replaced 3 Way Connector Now Ok When Engine Cold Also Installed The Bosio Fuel Nozzles Injectors From Dieselgieant.com 30x5=$150.00, Improvement In Power And The Trans Shift Improve Due To Less Movement Of The Vacuum Control Valve On Top Of The Injection Pump. Good Power Also Good Shift

B2 piston affects all forward gears usually----not likely your problem.

K1 kit affects 2/3 flare-----not likely your problem.

K2 spring affects 3/4 flare---not your problem.

B1 accumulator control valve spring affects 1/2 harsh shift-----YOUR PROBLEM

The harsh 1/2 shift (particularly when cold) is a "feature" of the 722.3 and 722.4 transmissions, not viewed as an unusual problem by MB, however, most US driver's don't like it, particularly as we (and the transmission controls) age.
The vacuum system should be checked, but you actually sound in range (as best I can understand; not being there). Should be 21-23"Hg at the pump hose. There is a "disc" tool to place on the vacuum control valve (white thing on IP) that sets a space between the lever and the stop pin. Vacuum with the tool in place should be 5.5-6.5"Hg at the valve. There is a very very sensitive adjusting screw under the bullet cover on the side of the vacuum control valve. Don't adjust it w/o the tool and a thorough understanding.

PROBLEM SOLVER?:
There is a valve body "shift kit" from Superior Transmission Parts Inc. that includes springs and instructions on how to soften the 1/2 shift w/o even removing the valve body. It has replacement springs for many of the valve body controls, but the one for the B1 spring train sounds like your huckleberry.

Here's a scan (not great) of some of the kit and the disc tool.

Here's the disc dimensions from the tran manual.

Here's the kit:http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=2&Product_Code=S68165D&Category_Code=722-3vbkits&Product_Count=1

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Attached Files

Pages from trans_manual.pdf (59.3 KB, 140 views)

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)