Cool build, have ?s need input.

[F-body Demon]

Hey guys so ive been working on this truck of mine for a while now and heres what I got and the questions I have not been able to find answers to via the search button.

Its a mystery 82 4x4 bottom lifted 6 inches with a 74 top. Running a re-built Bulletproof TH-350 and stock t-case, with a 400 sbc bored .030 running a 224/234 duration cam and a set of dart pro 1 heads vic jr and a holley 780 vac secondary making an estimated 550 crank hp at 6200 rpm. Im looking to run her in desert racing like prerunning.

Now what I wanted info on is the t-case, I got to wondering if it will hold all that engine? It has locking front hubs, which a friend of mine told me means it has a gear drive t-case...which to my knowledge are stronger than a chian, however is that strong enough?

Lastly it has a 10 bolt front axle and a 12 bolt rear, can anyone tell me if that makes it a 3/4 ton or what? There is no VIN or RPO on it being that the engine is gone the tranny is new and all im left with is a frame axles and t-case.

Any info is GREATLY appreciated! Thanks yalls!

[Blazin]

What do you mean by a 74 top? Is it a 74 cab?
 81 was the first year for the 208 t cases to show up. If its the original case it would be a NP 208 in a half ton. They are aluminum housing and not noted for their strength. They are chain drive. I have abused them and they held up. I have also blown quite a few of them into little bits and parts. Just because it has locking hubs does not mean its gear drive.
 3/4 ton trucks all came with 8 lug up until 87. after that you could get a light 3/4 ton with 6 lug or a heavy 1/2 ton with 8 lugs. Late 70s saw the change from a Dana 44 front end to a 10 bolt front end 1/2 or 3/4 ton. The rear is most likely a semi floating 14 bolt. They use C clips to retain the axles like a 10 or 12 bolt 1/2 ton rearend. The axle supports the weight of the truck, and drives the wheel. If you can see the bolts on the end of the axle that retain the axle to the drum / rotor assembly then its a full floating rearend. The housing supports the weight of the truck and the axles only purpose is to drive the wheel in a full floater.

[Captkaos]

I think that your estimated horsepower is very optimistic given the information you provided.
A 224/234 duration cam generally has a power range of 3000-6000 rpms and will probably be leveling off with the peak power closer to 5000, not at the redline.  Depending on the rest of the components you potentially would have close to 400 at the crank.

Locking hubs mean just that, you can unlock the hubs.  It has nothing to do with the style of transfer case, short of the 203.  There are 3 transfercases offered by GM during 1973-1987: NP203, NP205 and NP208.

NP203 is a cast iron fulltime case with aluminum caps, chain drive
NP205 is a cast iron part-time case, gear driven (it has a three bolt cover over the idler shaft)
NP208 is a part-time case, chain driven

The NP205 is by far the strongest.

10bolt front/12bolt rear verifies the truck in the 1977-up range (73-76's were Dana 44's)  It also makes it a 1/2 Ton truck.  If everything is from 1982, you have the aluminum NP208 transfercase, which is know as the weakest, You can beat on it for a little while, but.....

[F-body Demon]

Okay cool, so most likely it would be a good idea to go get a 205 t-case then eh. What year and models would I look for at the yard?

[VileZambonie]

If you have a 208 just keep it. You'd have to change your driveshafts too and what's the point? I have a 208 in my 3/4 ton and I've had the 208 in several of my 4x4's. I never broke one and I did some pretty aggressive wheelin in some of them.

[76_Scottsdale]

First figure out what TCase you have and if it isn't the NP205, swap that sucker.