Author Topic: Th400 to 4l80e in 1987 Sierra.  (Read 2682 times)

Offline thelittleguy94

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Th400 to 4l80e in 1987 Sierra.
« on: May 12, 2012, 04:17:37 PM »
Hey guys Jeff here I'm new to the site and I'm gonna be swappin in a   350 tbi from a gmc vandura instead of the 77 smogger thAts in it right now. Since I'm only 17 and this is my dd I thought it would be nice to have the 4l80e tranny with overdrive too.  My truck has an np208 transfer case. Anyone do this swap any help would be greatly appreciated.
-Jeff

Offline VileZambonie

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #1 on: May 12, 2012, 04:20:05 PM »
You can or you can go with the 4L60 since they both came factory behind a 5.7L if you are using donor parts. What trans was behind the TBI system?
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Offline thelittleguy94

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #2 on: May 12, 2012, 04:23:26 PM »
I picked up the donor it was ready for the scrapyard with a crack in the frame and that has the complete tbi motor and the 4l80e.  I also have an older 700r4 but i'm thinking if i get the computer out of the donor the 4l80e should work.

Offline VileZambonie

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #3 on: May 12, 2012, 04:25:57 PM »
Yes, it will. I have two donor 4L80E set ups. One is from a big block one from a small block. I would do the swap as well. You will have to figure out driveshaft length.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline thelittleguy94

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #4 on: May 12, 2012, 04:27:43 PM »
I thought so thank you, and yeah i'm not really looking forward to that.  Should it bold up to the np208 fine?

Offline VileZambonie

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #5 on: May 12, 2012, 04:31:41 PM »
As long as it's a 4wd Trans. What was it mated to? a 241?
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Offline thelittleguy94

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #6 on: May 12, 2012, 04:34:11 PM »
I believe so not entirely positive though I'll have to go take a look.

Offline thelittleguy94

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #7 on: May 12, 2012, 04:40:53 PM »
One from a 2wd application won't work?

Offline VileZambonie

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #8 on: May 12, 2012, 08:05:29 PM »
Not unless you convert it. You need the output shaft and extension housing
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline thelittleguy94

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Re: Th400 to 4l80e in 1987 Sierra.
« Reply #9 on: May 12, 2012, 08:46:22 PM »
Okay thank you i really appreciate the help ive found my way around the trucks pretty well but this is the first time i'm planning something this big thanks again