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i have an early 80s 350 behind a 350 engine. the problem is i drove the truck home one night and all was fine the next morning it would not shift into third. i have had this problem before and it was a broke vaacum hose to the mod, the line was fine. how do i check the modulator. thanx
 

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studebaker46 said:
i have an early 80s 350 behind a 350 engine. the problem is i drove the truck home one night and all was fine the next morning it would not shift into third. i have had this problem before and it was a broke vaacum hose to the mod, the line was fine. how do i check the modulator. thanx
The transmission shifts by governor. The modulator over-rides the governor. If the mod line is disconnected, only the governor works (5000 rpm shift).

Connect the mod hose to the manifold vacuum and drive it.
 

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studebaker46 said:
i have an early 80s 350 behind a 350 engine. the problem is i drove the truck home one night and all was fine the next morning it would not shift into third. i have had this problem before and it was a broke vaacum hose to the mod, the line was fine. how do i check the modulator. thanx

vacuum pump of the hand held type will pull a vacuum on the modulator. IF it holds the mod is good.

Pull the vacuum hose off first for a check for any trans fluid out of the hose nipple on the modulator..... trans fluid there equals an internally bad modulator.
 
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