driveshaft or transmission?


Asked by Mar 30, 2017 at 02:08 PM about the 1985 Chevrolet C/K 10 Silverado LB RWD

Question type: Maintenance & Repair

Okay so I have an 85 c10 Silverado long bed that has around 178k miles. Its a 5.0 350 engine and had a 700r4 tranny. The tranny I just took out was a 700r4 and I replaced it with the th350 that was almost new with no problems. I checked and made sure everything was connected and tightened correctly but I used the 700r4 driveshaft instead of the one the th350 had on it and I finished everything today and just put fresh fluid into it and a full tank of gas and when I put it into reverse I have to rev it really hard for it to even start reversing then it moves extremely slow and I can hear and see that all the gears are shifting correctly and the driveshaft moves in neutral but when I put it in reverse it doesn't spin. any suggestions should I replace the driveshaft with the transmissions original driveshaft?

4 Answers


Were the splines the same on the two drive lines? If not you probably ruined the output shaft on the transmission. Why would you put a light duty turbo 350 in your truck?


the spline on the one I put on was just a hair longer the only reason I put it on there was because it was painted and the other was rusted and I put the 350 in it because the 700r4 was slipping and wouldn't go into 3rd gear or over drive and you'd have to rev it to get it into 2nd


If the driveshaft properly fits the TH350 then there is a problem with the used/ new transmission. I assume you check the fluid level?


yes I just changed and refilled the fluid, and there couldn't be anything wrong with it I drove it here in an 86 Scottsdale for about 45 mins and didn't have a problem with it, everything bolted up correctly the only difference was the driveshaft was slightly longer than the 350s drive shaft

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