4L80E with Th400 driveshaft and fuse box questions

[Nodnarb76]

The parts are piling up In my house now, motor and trans should be here soon from LSX4U.
Couple questions for the experienced ls swappers.

My swap will be an LQ4 4L80E into an 87 R20 2WD Suburban originally equipped with a 454 and Th400.

1. Using the dirty dingo slider mounts will I have to shorten or lengthen my driveshaft? Sounds like my Th400 yoke will work with the 4L80E, just wondering what might need to be done?

2. Probably a dumb question. Once I remove the stock TBI harness, I should still have power my fuse box right under the dash correct?

Thanks in advance.

[Nodnarb76]

anybody?

[ls1nova71]

Originally Posted by Nodnarb76

The parts are piling up In my house now, motor and trans should be here soon from LSX4U.
Couple questions for the experienced ls swappers.

My swap will be an LQ4 4L80E into an 87 R20 2WD Suburban originally equipped with a 454 and Th400.

1. Using the dirty dingo slider mounts will I have to shorten or lengthen my driveshaft? Sounds like my Th400 yoke will work with the 4L80E, just wondering what might need to be done?

2. Probably a dumb question. Once I remove the stock TBI harness, I should still have power my fuse box right under the dash correct?

Thanks in advance.

1. Just put the engine in and measure would be your best bet. Not much you can do about it either way before you do. Having a driveshaft made or shortened before seeing exactly what you need is asking for trouble.

2. Your fuse box is powered by the front engine compartment harness so you should still have power to it after removing the TBI harness.

[Nodnarb76]

Originally Posted by ls1nova71

1. Just put the engine in and measure would be your best bet. Not much you can do about it either way before you do. Having a driveshaft made or shortened before seeing exactly what you need is asking for trouble.

2. Your fuse box is powered by the front engine compartment harness so you should still have power to it after removing the TBI harness.

This is what I thought, just was not sure if someone had done this exact swap before and knew that they were able to reuse their driveshaft. I already have a custom driveshaft in my budget just in case, but if there is anything I can get before the swap starts to make it easier/cheaper.
thanks for the TBI wiring info, that is what I thought. Just trying to cover all my bases before I start turning bolts.

[BR3W CITY]

Originally Posted by Nodnarb76

not sure if someone had done this exact swap before and knew that they were able to reuse their driveshaft.

From experience, let me tell ya that 2 trucks with the EXACT same swap, can still have different results for things like driveshaft, exact header fitment, suspension settings etc.

There is nothing worse than being sure of something, and having it not actually work out. Not to mention that with an aftermarket DS, you have a bit of control over things like material, thickness and the sorts. My ds was made of over-thick wall steel and rated to just under 1khp. Aluminum, Carbon and other shafts exist for even more if you want to lose weight or put down insane power.

[clinebarger]

Your TH400 will have a "Bolt-On" Yolk, A 4L80E could either be a Bolt-On or Slip Yoke, If is a Slip Yoke 4L80E....You will have to source a slip yoke.

I can just about assure you the front part of your drive shaft will need to be shortened.

[Nodnarb76]

Thank you for all of the advice.
Found a local shop that I can have the truck towed to once I get the motor in, that should be able to take care of the driveshaft for me. Thank you all for the help on my project!

[Nodnarb76]

Well I called and they are out of business.
So now I'm going to either send it out to be cut, or get a new one.
Either way I'm going to have to measure a few things I'm worried I may not measure correctly.

[Advanced Design]

This should help walk you through the measuring....http://www.dennysdriveshaft.com/how_to_measure.html

[ls1nova71]

Measuring is not hard at all, BUT, measure it the way your particular shop wants it measured! Some shops want a measurement from the tailshaft seal to the center of the rear u joint, where as some will want you to measure from u joint center to center. Just find a shop near you and talk to them first, you'll be fine.