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I recently inherited an old 87 S10 Blazer from my grandfather that hasn't moved in 20 years. It has a 2.8L TBI V6, T5 Manual and 4WD system. My initial plan was to drop a Vortec 4.3L into it but after doing some research on the Blazer forums that's just as labor intensive as an LS Swap. I'd like to use the car to tow my other cars to and from the racetrack, I have a Twin Turbo Corvette I road race and a stock LS1 02 Trans Am that I'd like to convert to a dedicated drag racer once it's no longer my daily driver. I have plenty of stock LS2 parts and accessories in boxes from the Vette and plenty of experience working on LS engines (in cars that came factory equipped with them), I'd like to retain the 4WD and Manual (even if it's not necessarily the one that came in the truck) but I'm finding a lot of mixed information on what it takes, what's possible, and what power certain components can hold. Most threads on this in the Blazer forum are also over 10 years old which is why I've begun to fish for information here.
To summarize, just need to know where to start looking for a manual trans (5 or 6 spd) and transfer case that will mate to an LS, live at approx. 350-400 whp, and fit in my 2 door Blazer. Assume medium budget and no real timeline, I expect this project to take 1 to 2 years. Pic of the chassis for reference.
Couple of considerations. Those blazers didnt tow great when they were new, a fishing boat - sure, but not a car trailer. I really prefer tow vehicles that are big, heavy duty, and rock solid. After swapping the entire drivetrain, youll need to do rear and suspension. The truck youll be getting your drivetrain from is probably the truck that will will make a great tow vehicle.
Not many manual 4x4 gas engine trucks were made. If you do find a manual trans, 4x4, gas engine silverado, get the whole truck, youll need all of parts you can get to make this work.
Most likely an NV3500 trans(1/2 ton), expect to rebuild it, anyone that ordered this truck used it hard.
Couple of considerations. Those blazers didnt tow great when they were new, a fishing boat - sure, but not a car trailer. I really prefer tow vehicles that are big, heavy duty, and rock solid. After swapping the entire drivetrain, youll need to do rear and suspension. The truck youll be getting your drivetrain from is probably the truck that will will make a great tow vehicle.
Not many manual 4x4 gas engine trucks were made. If you do find a manual trans, 4x4, gas engine silverado, get the whole truck, youll need all of parts you can get to make this work.
Most likely an NV3500 trans(1/2 ton), expect to rebuild it, anyone that ordered this truck used it hard.
From what I've read most 4WD LS guys are using the NV3500 or NV4500 so that's probably the route I'll go. I know a bigger truck would be more efficient but to be completely honest I'm not a fan of trucks or large vehicles in general and this one holds sentimental value which is why I'm inclined to keep it around. What would you recommend in terms of strengthening the rear? I had planned a total overhaul of the suspension anyway simply due to the age of all the components.
Look at what Jeep guys have done, as they are not so different to S10s. Novak Adapters has some good guides.
There's a big difference between a NV3500 and NV4500. NV3500 or 3550 could be reasonable. NV4500s are big heavy monsters with granny low firsts and would not make any sense in there. Unless your primary purpose is to tow. Towing with manual transmissions sucks in general. Jeep NSG370 might be a viable option if you don't go crazy on the HP and don't beat on it.
Rear axle, you'll need to measure, but usually the cheap strong option for most narrow solid axles is a Ford 8.8 from an explorer. You'll need to re-drill the axles/discs, but that's pretty standard
After about an hour and a half of research on Novak I'm pretty much sold on the NV3500 or NV3550 but my only concern is the compatibility with the transfer case. The NV231 transfer case that came in my Blazer is up to the job in terms of power capability but the front face has a 5 bolt pattern while the Jeep NV3550 has a 6 bolt and maybe I'm using the wrong search terms but I haven't found a conversion kit. If perform a direct swap with a Jeep NV231 I run into a similar issue with the spline count on the input shaft and I'd hate to buy a whole new T-Case if mine is up to the job. Gonna do a little more digging on this but so far off to a good start.
I'd just get a Jeep NV231. They are cheap, probably can grab one for $100 or less, there's a couple million of them. It's been a while since I went through all of the variations. You may be able to swap input gears if you need to make a custom setup.
Rearend, its been a while since I messed with blazers or S10's. There was a 7.5, 7.625 and 8.5 ring gear version of S10 and Blazer rears. Earlier vehicles and 4 cyl got the smaller rears, werent a lot of 8.5 rears to begin with, any that were sitting around have been grabbed by 4x4 or V8 swap guys.
A lot of stick shift S10's destroyed the smaller rear ends without much abuse.
See what you have.
8.8 is a popular swap, with new axles or drilled flanges and associated brackets.
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LS Manual 4x4 Blazer 
