LS swap transmission choice

[iamtherealJayy]

I’ve started the tear down on a 99 Sierra with a 5.3 and I assume 4l60e. I’ve got the harness and ecu out and taking it to Murray to be flashed this morning. I’ve done the ls swap in my k10, but I used a manual trans. This blazer was originally a 6.2/700r4/208, it now has a 350/400/208. I want to use the newer trans to keep the engine as original as possible. Would the np208 bolt to a 4l60e? Should I reconsider and retain the leaky th400? I’m building this truck for reliability. I want something I can trust the ole lady to go to Walmart in. The manual ls swap wasn’t involved as much as this, so I’m not positive if I need new cross members or adapters or whatever else. All in all with the entire fuel system and having the ecu flashed I’ll only be around $800 in the swap. I don’t care about speedo etc at the moment, so long as the ecu knows how fast it’s going I’ll be suffice. If I use the 4l60e it tells the ecu how fast it’s moving correct? Then I can just retain the cable from the np208? Will the stock shift linkage work? This will be a bone stock 99 5.3 so I’m not worried about over powering the trans.

 

[Camar068]

-yes the 4l60e will bolt to a NP208, use the 4L60E adapter, not the older. BIG PROBLEM will be is the spline count on the NP208 and the 4L60e the same? I believe the 400 will have a different spline count. No biggie, just go get another np208 with the correct spline count for less than $200.

-the 4l60e isn't going to tell the ecu how fast it's going. you need to install a VSS sensor somewhere. I pressed a reluctor wheel on the output of the trans and drilled a hole for the sensor in the 4L60E adapter. There are other ways, google is your friend. Either way, your going to need a signal.

-stock shift linkages should work as the 4l60e is an upgraded (multiple times) 700r4.

Figure out the spline count, then tackle the VSS signal solution and work your way down the list of your Q's before you pull the trigger on ANY of it so you know exactly what $ your out.

 

[Camar068]

NP208 info:

https://www.midwesttrans.com/product-information/np208-transfer-case

 

[iamtherealJayy]

Previous owner swapped in the th400, which has a 32? Spline? I asked him the other day if he still had the 700r4 and original tcase so I gotta go get that for another $200, no biggie. I’ve done a manual swap, but I’d rather have an automatic for the “goin to town” rig, I need something the ole lady can drive too lol. I tried reading multiple forums about the automatic swaps but majority of them are c10’s. I’m stuck between something similar to how I did my k10, Dakota pass through vss, or going with an advanced adapters with vss. I’m fine with either I just need whichever is most efficient. I haven’t done the adapter before so what speed sensor would I need? I also couldn’t find any solid answer about shift linkage or trans crossmembers. I’m positive I want an overdrive trans whether I have to run a 700 or a 4l60, I’d rather do the 4l60 because I’ve got one that’s already connected to the 5.3. I do have to replace the range selector neutral safety switch on the side however. As I get farther into the swap I’ll make a list similar to the one I did on my k10 telling what I used and how it went. Main things I’m after is keeping the stock driveshafts if possible, the blazer has a 6” lift so even pushing the driveline back and inch or so would be better than forward, I can live without a front driveshaft for now.

 

[dvdswan]

I run a 4L60E with a 5 gear planetaries (from a 4L65e) instead of the 4 gear it comes with and a NP241.

 

[wlwarnke]

I used the advanced adapter for VSS when I swapped to a 4L60e. Makes the 6 bolt ass end of the 4L60e look just like the 4 bolt 700r4 and adds a speed sensor. Kept the crossmember and everything in its original location as the 4L60e was like 1.5” shorter and the adapter measure 1.5” thick.

 

[wlwarnke]

Factory shifter should work just fine. Won’t need the PN switch as it was built in to your column. TCC brake switch should already be there also.

With the VSS before the xfer case, your speedo won’t be accurate in 4Lo but Tranny will shift normal.

 

[Craig Nedrow]

I have blown two 4l60e in lightly moded 1998 Camaro, not a fan. Got a 2004 4l80e, $500 Seattle area, 45000 miles. It is going behind the BB and using a US Shift quick 4. Here are what is required:
Quick 4 controller - $585
Main harness w/loom - $150
TPS Adapter for carb - $175
These are fully programable, and have an excellent rep., and fantastic CUSTER SERVICE!!!
Web site:

US Shift Stand-Alone Transmission Controllers

US Shift Electronic Transmission Control Systems let you take charge of your 6R80, 4R70W, E4OD, 4R100, 4L60E, or 4L80E transmission and unlock its true potential. Our transmission controllers are compact, packed with features, and have a built-in display for tuning as well as user-friendly...

www.usshift.com

 

[Camar068]

I do have to replace the range selector neutral safety switch on the side however.

You can delete the range selector NS switch if you like. I think it's only one wire that needs to be put in place. I did this to eleminate stuff to troubleshoot later. Although it might be easier having it with cruise. I'll let you research that one, but I don't think it's required for cruise.

Look and the pro's/con's of both and make your own decision. I'll check, I may have a brand new one I purchased before I deleted mine.

 

[Camar068]

I run a 4L60E with a 5 gear planetaries (from a 4L65e) instead of the 4 gear it comes with and a NP241.

didn't know that, thanks for the info. I'll upgrade mine if/when it's rebuilt.

 

[tahitiansoul]

NP208 electronic VSS conversion kit (R2) | Walters Engineering

Electronic vehicle speed sensor conversion kit for mechanical speedo drive, NP08 transfer cases. Removes the mechanical speedometer driver hardware and replaces it with an electronic vehicle speed sensor. Our conversion kit is a 100% bolt on installation that does not require any irreversible...

www.walterseandp.com

this is the adapter I bought to get VSS signal for my Dakota digital gauges, to work also with my 2008 4L65e.
My 1981 NP208 transfer case connects to the 4L65e with the adapter that came with the transmission.

 

[Matt69olds]

didn't know that, thanks for the info. I'll upgrade mine if/when it's rebuilt.

Just make sure you are buying GM 5 pinion gearsets. The China versions are made from glass.

 

[wlwarnke]

I have blown two 4l60e in lightly moded 1998 Camaro, not a fan. Got a 2004 4l80e, $500 Seattle area, 45000 miles. It is going behind the BB and using a US Shift quick 4. Here are what is required:
Quick 4 controller - $585
Main harness w/loom - $150
TPS Adapter for carb - $175
These are fully programable, and have an excellent rep., and fantastic CUSTER SERVICE!!!
Web site:

US Shift Stand-Alone Transmission Controllers

US Shift Electronic Transmission Control Systems let you take charge of your 6R80, 4R70W, E4OD, 4R100, 4L60E, or 4L80E transmission and unlock its true potential. Our transmission controllers are compact, packed with features, and have a built-in display for tuning as well as user-friendly...

www.usshift.com

My buddy just used one of these for an A4ODe (I think) swap behind a 400M in a 79 Bronco. Works flawlessly.

 

[Craig Nedrow]

Thanks for sharing that William, hope the same for me when my time comes.

 

[iamtherealJayy]

I think I’ve decided on a 4l60e, I don’t care about cruise I’ve never had it so don’t see why I should make it a priority now. I think I’m going to go with the advanced adapter piece but I need to find a tailhousing off a 700r4. I want the vss to be reliable so I don’t really want to run an adapter from the speedo cable. I do plan to retain factory gauges for the time being atleast. (Wasn’t in the budget for the build) I however did notice my shift linkage, on the frame side, is not in its little hole with the bushing and spring. Can I buy this spring somewhere and fix it? Or should I swap linkages completely? I’ve ordered roughly half of what I need to do the swap and after I’ve got everything I need I’ll make a list similar to my k10, parts, how they worked, etc. for those who want to attempt the same thing.