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About a week ago I was pulling away from a light at about half throttle and when I shifted from 1st to 2nd the rpm's kept going. After that I had nothing but park or neutral, checked linkage and inside the pan- nothing abnormal. Any idea's what happened ? Also I've since bought a rebuilt C6 from a friend that was in his 390/69 Mach 1. The new trans. is about 1 inch shorter than the one in the car, is this any need for concern ? Thanks.

67 GTA 390 Fastback- Moss Green
Deluxe black interior.
 

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The shorter tranny would be a concern, your drive shaft won't fit. It'll be to short. As for your loss of go-motion, check the vaccum lines to the tranny, if they're good, smell the tranny fluid on the dip stick. If smells burnt, trust me you'll know if it is, then you're tranny's cooked. You could probably just swap the tail sections on the two tranny's then put the rebuilt one in. But make sure the one in your car is no good before you start to pull it out!

68 fastback, 390 4V premium fuel
80 5.0 hatch, just finished
91 5.0 coupe, daily driver
84 RamCharger 4x4 extreme mudsliger and winter junker
 
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There was no burnt transmission oil smell. The only vacuum line is to the modulator valve. I'm quite sure it's still hooked up, but even if it wasn't would it cause me to lose all the gears ? The only thing I found was a pinched transmission cooling line to the back outlet. The new transmission is only 1 inch shorter and I always thought the driveshaft was too tight to fit in before. Thanks.

67 GTA 390 Fastback- Moss Green
Deluxe black interior.
 

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My first impression is that your trany is cooked. From the ones that I have rebuilt in the years past, a simple o-ring in side one of the clutch drums would break and then your done. You can't swap the tail shaft housings and make this other trany work. The out put shaft needs to be changed out as well. In order to do this, you would have to tear down the trany. Sounds like you need to take your old one and have it rebuilt. I have also seen many of the intermed bands inside the trany let go. Sometimes this can be fixed without a complete tear down. Sometimes it would be the servo that operates the shift band as well. How much do you know and feel comfortable with doing on your own? If you want, you can call me and maybe I can help more. See my profile and then my homepage for a phone ##. Denver
 
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