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Axle swap dilema

3

398HBX

1/2 ton status
Joined
Jul 17, 2010
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Location
Oak Ridge, TN
I recently returned fro CA with a 1986 Suburban towing a 1973 Blazer. I no longer need the burb but after reading what several people have to say about axles, I am considering parting out the truck and using the burb axles on the Blazer. The Blazer has 12-bolt rear and Danna 44 front. I have no idea what the burb has for a front axle but it does have a 14-bolt rear. I know the 14 bolt would be better in the long run but my wife would kill me if I had another vehicle sitting around on blocks. I plan on building the Blazer as a street/dirt vehicle with most of the time on the street but not afraid to take it on the trail. When I go on the trail, I want to be able to go. I started abuild site before I found this one, www dot 398hbx dot com. If you could take a plook at my plan and let me know where I am screwing up or if you have any thoughts on the axle swap, please let me know. I really need the help.

Any thoughts?
 
Just take and put the burb axles (front and rear) and put them in the blazer. Then put the blazer axles (front and rear) in the burb and sell the burb. Everything will bolt right up. You'd have to get a conversion u-joint for both rear axles at the yoke.
 
I plan on putting on 35" tires. Should I also swap the T-case and transmission? The Blazer has a NP203 with a TH350. The burb has a NP208 and ? for a transmission.
 
I would swap the tranny/tcase unless you really want that overdrive that bad from the 700r4 the burb has. Besides doing that you'd have to have new driveshafts made.
 
He said it's a 86 Burb and probably a 3/4 ton so it should have a TH400.
 
Yes, it is a 3/4 ton. Overdrive would be nice since I will be doing a lot of driving on the road as well as off road. Some threads I have read kinda trash the NP208 as not being as durable as the NP203. I plan on putting in the Mile Marker part-time kit for the 203 though. Other than the axles and T-case, are there any other major parts that I should consider swapping?
 
398HBX said:
Yes, it is a 3/4 ton. Overdrive would be nice since I will be doing a lot of driving on the road as well as off road. Some threads I have read kinda trash the NP208 as not being as durable as the NP203. I plan on putting in the Mile Marker part-time kit for the 203 though. Other than the axles and T-case, are there any other major parts that I should consider swapping?
Click to expand...

203s are garbage and good for nothing but the range box for a doubler. 208s only downfall is the slip yoke that being as long as your not running big power.
 
The engine that I am building for it will be a 383 stroker, so there should be plenty of power. I'm not sure if that would be a problem for the NP208.? At this point in my build my options are pretty unlimited. I picked up the 86 3/4 ton for $1000 just to tow my Blazer back to TN. I could probably sell it intact for $2k. That's my dilema, do I sell it and use the cash to buy more engine parts and upgrades or use it as a parts truck?
 
Stomis said:
203s are garbage and good for nothing but the range box for a doubler. 208s only downfall is the slip yoke that being as long as your not running big power.
Click to expand...

203's are not garbage. I've owned several of them and have never had problems. 208's are chain cases just like the 203.
 
I say do like Muddytaz said and swap the parts over between the two. Put the half ton axles and drivetrain under the Burb and then sell it as a running, driving half ton.

208's aren't grenades or anything. As long as the chain isn't loose, the fluid is full, and there's a skid plate you're fine. Plenty of folks on here have run them behind big blocks, diesels, and other high torque engines doing all kinds of things. There's a point where you want an Atlas, LowMax 205, or what have you but if it works correctly then it's simpler and lighter along with a better low range.
 
I don't know about the 203 out of a 73, but I had a 78 with a 203 and had zero problems with it. Other than fuel economy, I would guess most complaints with a 203 revolve around the shifter.
 
I think I have decided to swap the axles from the 86 3/4 ton Burb to the 73 1/2 ton Blazer. I looked in the burb and found that the 14bolt rear-end has 4.10 gears. I am assuming that I need to change the front axle as well so the gear ratios match. Also, I will swap the NP208 from the burb over to the Blazer. Do you think that there will be any problems connecting to a B&M TH350 tranny? I know that I will have to change the driveshaft length, but that should be easy to find someone to do that. Also, do you know if the windshield fro the burn will work on the Blazer? Please advise.
 
I know that I am full of questions and I really appreciate all of your responses. I have another question. The front end on my Blazer will need to have the front quarters replaced. The ones on the 86 burb are in mint shape. Will they fit? If so, should I swap them or try to leave the Blazer looking as original as possible?

Thanks
 
Don't forget you will need to use the burb's wheels because it will now be 8 lug not 6, so yes to changing the front as well. Don't know fenders and glass (I'm a 1st gener). It would be nice if it was a TH400 trans(Just stronger,stroked 383 will have some good HP coming from it) but either way you will probably need an adapter to match the trans to the TC.
 
If you want to swap the t-cases then you will want to swap trans's also. The NP208 behind the TH400 will have a different input shaft and will not work with the TH350. If you plan on building a stout 383 you will want the TH400 behind it anyways.

So, if you swap the TH400/NP208 from the Burb into the K5, the front driveshaft from the Burb will also work in the K5. Then you will only need to buy a rear driveshaft which will save you some money right there.

4:10 gears should work good with 35" tires and no overdrive trans. And yes, swap BOTH axles so that gearing and wheels/lugs match.

I do believe the windshields from Burb to Blazer are the same, just not sure if the early full convertible Blazers were the same as the later 1/2 cabs.

The front fenders on the Burb are different because of the year. You could swap them but you would have to swap the whole nose, (fenders,hood,grille,radiator support) basically everything forward of the windshield and doors. I would think it would be easier to just purchase some replacement fenders, which would also keep the original look.
 
Thanks for the info. It helps. Will I also need to change the tie-rods, steering arms, etc? I am a little leary of swapping out the TH350 for the TH400, but then again, I am a newbie. The reason being is that I have a new B&M TH350, torque converter, deep pan, etc that I got form my father-in-law with the truck. The TH400 on the burb worked well during my trip back from CA but it does shift hard. I hate to see brand new parts just sitting around. But if you think I need to use the burb tranny to make life easier, then I guess that is the route I will go. Anybody need a TH350?
 
Define "shifts hard"?

Reason I ask is my dad swore up and down my TH400 in Big Ugly shifts hard. Turns out he's just old and used to minivans.
 
It shifts hard when shifting out of park. Also when driving, it sometimes will not shift down. I think that a good flush and fluid exchange should fix most of the problems. My other car could be considered a minivan, it's a 95 K2500, Suburban, 4x4, 454, HD variant. :). AFter doing more reading, I am getting pretty excited about the whole axle, tranny, t-case swap. I think it will make the Blazer a much better overall vehicle. Now I just have to finish building the carport...
 
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