I just picked up a last 60's early 70's 3/4 tonne chev. the rear axel is the corporate droupout style that is described in the "bible" the front is a closed knuckle 44. The guy I got the rig from says that it is a 72 but the "bible" says that chev only used the closed knuckle up to 1970. Also does anyone have any info on the dropout corp rearend? It's massive and looks like a 9" on steroids with a removable cover of course.
I got the aviable ratios from the "bible" but what size is the ring gear and the shafts ect....

It has a 327 small block and a 4speed granny gear box and a np203 t-case. I'm pretty sure the gearbox is a sm420. This would indicate that the truck has to be a 69 and older..

If anyoen has any links of info could they post it here please.. Also any opinions on running the stock rear end.

Thanks......
Jonathan

all of those parts sound strange
np203 4 speed, are you sure?

I'll take a stab at this.
AFAIK up to 72 used the closed knuckle, 73-76 had external hubs on 3/4 ton and they came open knuckle with disk brakes.
The rear axle is an old Eaton, typical of those years.
One big mother fawker, I believe that the ring gear diameter is like 12". You might get lucky and it will have a Detroit in it.
Alot of Eaton axles came with them from the factory.
The only draw back to those big pigs is parts availibility.
My supervisor has a 69 that has a 14FF in it. he says that it is original but I had a 69 3/4 ton and it had the Eaton in it.
The gearbox and t-case, if original should be a 420/205.
Here are pics of the 203 and 205 with info on IDing each.
http://www.chuckschevytruckpages.com/drivetrains.html
You do realize that the rig is 30 years old and alot of swaps could have happened in that time frame.
The fact that the Eaton is still in it is a testiment of it's strength and duribility.
Big Burb (I hope that's his name) Won The TTC with his 72 and it has an Eaton in it.
If it was me getting this rig I would keep everything but the front axle.
That I would swap out for one from 73 on.
Just because messin with a closed knuckle is a pain in the ass.

Thanks for the info powermad....
It's a eaton for sure and it's massive. the axel looks in good shape except for the backing plates..hopefulli i can swap some 60 of 14 plates on if i can't get parts for the eaton..

The tranny is the sm465 it has the ribbing on it ans 2 PTO ports. The t-case is the np203 by the pick on the chey link u posted..

The front is a closed knuckle 44. It drives like a frigging tank LOL. how do i tell if there is a locker in the eaton, spin the wheels when they are jacked up and see if they turn in the same direction?

Do you have any links to parts supppliers for the eaton..

I'm going to get a 8 lug 44 to swap in for sure something with discs. I'll just swap the gears from the old one..

Any info on the 327 that is in it...HP and tourque specs...

Thanks in advance...

Also is it hard to bolt up a np 205 so I can go with part time 4wd? Will it bolt to the factory adapter that is there for the np203?

If it's a 72 3/4 ton it should have come with an open knuckle and disc brakes. That 203 shouldn't be there either. Sounds like someone blew up the old tranny and swapped in a newer one, the 203 is probably still on their cause they didn't have the factory adapter for the 205.
I don't know to much about Eatons but my friend had one in his 72 that ate the ring gear and if I remember right it had coarse spline axles, not positive though.
You'll know if the truck has a detroit in the back the first time you put it in on the road, if your not positive jack it up and see if the tires both spin in the same direction.

the 465 w a 203 is one valuable piece
rare and required for doubler
you could straight trade it for a 205 with zero problem