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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: thelittleguy94 on May 12, 2012, 04:17:37 pm

Title: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 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

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: VileZambonie 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?

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 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.

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: VileZambonie 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.

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 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?

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: VileZambonie on May 12, 2012, 04:31:41 pm

As long as it's a 4wd Trans. What was it mated to? a 241?

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 on May 12, 2012, 04:34:11 pm

I believe so not entirely positive though I'll have to go take a look.

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 on May 12, 2012, 04:40:53 pm

One from a 2wd application won't work?

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: VileZambonie on May 12, 2012, 08:05:29 pm

Not unless you convert it. You need the output shaft and extension housing

Title: Re: Th400 to 4l80e in 1987 Sierra.
Post by: thelittleguy94 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