You may get the results you are looking for by adjusting the modulator on the trans. Considering that you are 'slipping' in reverse is a sign that it may be a good idea.


However, I think its best to get the vacuum system working properly before adjust the modulator though.

adjust the vacuum control valve to spec (the write up for the shift kit is a good source)

test vac system for leaks

adjust the vacuum amplifier by feel (there is an adjustment key under a friction fit cap)

If you cant get firm shifts by those, then adjust the modulator.


Of course, the history of that modulator and trans is certainly up for scrutiny by now, and adjustments to the modulator may be corrective.


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Trans should be at operating temp.

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