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'86 Jimmy 4in Lift, 40’s, tons, 8.1 Swap- 700r4 said PNNNNN

This is not a dedicated trail rig, but does trailer to the destination usually. I am currently in the planning phase of doing a 52/56" spring swap, and getting back to being more road worthy.
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83ChevyK5Blazer said:
So whats phase 2?
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Well, so that’s where I was headed next!

The 8.1 is in and doing great, so the next step is getting the 4L80 in and figuring out what route to go with transfer case.

These are the T-cases I have at my disposal and the possible routes:

- 205 27 spline for possible magnum box OR
- 203 to make a 203/205 doubler
- 208 GM and 208 Dodge to make SYE 208
- 241 pass drop with VVS to also SYE

So my current debate is which way to go for T-case setup behind the 8.1/4L80E.
 
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I’ll also add that I am using a 2wd 4L80 which has the rear output for VVS, so transfer case VVS is not necessary.
 
Is your computer cool with the vss tone ring set up now?
There have been rigs in the past where they refuse to shift since the vss tone doesn’t match the engine speed vs math

Also planetary + 205 vote
 
Bent77 said:
Is your computer cool with the vss tone ring set up now?
There have been rigs in the past where they refuse to shift since the vss tone doesn’t match the engine speed vs math

Also planetary + 205 vote
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I’m currently still running my original 700r4/208. The wiring harness is wired for the 4L80 but none of it is hooked up. I have a CEL on for different transmission related codes, but have been ignoring that for now.
 
I’m looking at doing my T-case swap really soon. For now I’m swapping the 205 in behind the 700r4 as I’m not quite ready for the 4L80 and under drive unit.

I have this driveshaft sitting downstairs. It’s in good shape, but most likely will need to be lengthened. I’m thinking about finding the O.D. Of the tube and sleeving it with thicker walled tube that fits the smaller tube inside. Weld the ends as much as possible and maybe even balance it.

The flange would be pulled off the one end then bolted up to the factory yoke of the 205. Then the other single u-joint would bolt up just like factory.

Anyone see a problem with that plan?

IMG_8878.jpeg
 
Once I do the crawl box and 4L80, I’m just going to pony up for Tom Woods or similar. I just don’t want to spend all that coin just to have the expensive driveshaft cut up eventually.
 
My front driveshaft has a 2" pipe union welded in the middle of it lol. If I wanted to do one the best I could I would do sleeve and have it turned down on the ends to slip inside my driveshaft tube like 2" each way to make it as straight as possible then weld it.
 
6872xtc said:
May I ask why you want to swap the 205 in place of the 208?
I am just wondering why remove a better low range case?
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So here’s a little story I got to tell…

Eventually the truck is getting a computer controlled 4L80 behind the 8.1. Then some sort of crawl box and 205.

Right now the truck has a 700r4 and 208. The rear driveshaft is no longer usable. So, I’d have to do driveshaft work plus, the rear driveshaft is too short and my pinion angles are off.

Currently I can’t drive the truck very far or fast because there’s either something broken in the 208 or my driveline angles are that far off. I’m wanting to drive this more, further, and higher speeds. So the work involved to save what I is more that swapping to the 205 that I will be running long term.
 
GWeakland620 said:
So here’s a little story I got to tell…

Eventually the truck is getting a computer controlled 4L80 behind the 8.1. Then some sort of crawl box and 205.

Right now the truck has a 700r4 and 208. The rear driveshaft is no longer usable. So, I’d have to do driveshaft work plus, the rear driveshaft is too short and my pinion angles are off.

Currently I can’t drive the truck very far or fast because there’s either something broken in the 208 or my driveline angles are that far off. I’m wanting to drive this more, further, and higher speeds. So the work involved to save what I is more that swapping to the 205 that I will be running long term.
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Well the 205 is either a 32 spline to work with the 4L80E or a 27 spline to work with the 700r4.
If it's a 27, then it will not be too much work for now and I agree go ahead.
If it's 32 spline then you are better off making your setup work for now.
 
imiceman44 said:
Well the 205 is either a 32 spline to work with the 4L80E or a 27 spline to work with the 700r4.
If it's a 27, then it will not be too much work for now and I agree go ahead.
If it's 32 spline then you are better off making your setup work for now.
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You are correct. The 205 is currently a 27 spline.
 
GWeakland620 said:
You are correct. The 205 is currently a 27 spline.
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Is the shaft the right length to mate to the 700r4?
If it is too long I might have the right spacer for you.
If it's short I can't help.
You should have a female coupler because that 205 is a male input shaft
 
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