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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 86charcoalsierra on August 26, 2015, 02:05:49 am

Title: 1986 drive shaft
Post by: 86charcoalsierra on August 26, 2015, 02:05:49 am
I recently installed a 454 out of a 1985 Chevy Truck into my 1986 gmc Sierra. Also put in a 400r transmission out of same truck I had a 305 in my truck with the 350 transmission. I used the drive shaft that I had but it is about 2-3 inches to short. So it leaks alot of transmission fluid. Need some help on what drive shaft I can use or if any body know where I can get one around fort Worth tx. My truck is a short bed with stock differential. Thanks for the help.
Title: Re: 1986 drive shaft
Post by: Irish_Alley on August 26, 2015, 08:55:30 am
the way i see it your th350 should of been about 27 11/16" long the th400 is about 28 3/8" long. so the driveshaft should fit good, the problem you might be having is just a bad seal
Title: Re: 1986 drive shaft
Post by: 86charcoalsierra on August 26, 2015, 01:53:40 pm
I already replaced the seal. You can see in the picture that I need about 3 more inches I'll have to measure to be sure. The slip yoke is only about half inch inside transmission. The yoke on back of the transmission had a nut so it was flush with the back of the transmission. When I went to install drive shaft it was to short so I took the nut off and pulled the yoke out until it would reach. It's bearly in there pretty sure if I hit a good bump and catch some air the shaft Will fall off.
Title: Re: 1986 drive shaft
Post by: Irish_Alley on August 26, 2015, 02:13:43 pm
ahh so you had a bolt on yoke and now you have a slip. this changes things a little
Title: Re: 1986 drive shaft
Post by: 86charcoalsierra on August 26, 2015, 02:19:20 pm
Yes that's what happened any ideas.
Title: 1986 drive shaft
Post by: roundhouse on August 27, 2015, 07:25:05 am
Pick up the right shaft at a junk yard
Even if it's too long
Lot cheaper to get it cut down shorter at a drive shaft shop
You have to have a slip joint
Either in the shaft or in the transmission
But you can't have two

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Title: Re: 1986 drive shaft
Post by: Irish_Alley on August 27, 2015, 07:56:19 am
yeah thats about all i can think of. put the bolt back in the yoke and measure from yoke to yoke then go to the yard and find a driveshaft with a similar size and Basic stub and slip yoke type driveshaft