Any old Dodge mechanics online here

Is this a D300 or a W300 truck?
My memory says they used different brands of components. Spicer was one.

That is an old truck!

Wheels are different between single rear and dually, so front hubs will be different.

They will not interchange. Maybe including the cotter pin.

Old timer Dave
Do you mean Dually tires ( I think you do ) on the rear
Or
Dual = two rear axles
A third rear axle is called a tandem axle

My first motorhome was on a 72 Dodge chassis, 17" tires on all 6 wheels, front and back where the same wheel and tire,
Not positive but it might of had a Bendix design braking,, drums, shoes, and brake cylinders
I think it was a D300 chassis

Do your rear brakes have one brake cylinder at top of mounting plate
Or
Two cylinders ,
one at bottom and one at top

For each of the rear drums

Memories.

8.00 x 19.5" tires.

440 engine
A727 trans

One of the most stable towing platforms on the road

And best friends with a gasoline dispenser.

The spindle and ball joints may be different as well and may not allow the single wheel hub and rotor to be mounted. Keep looking for the right parts, they are out there somewhere.

Isn't the B series 'vans'
Other trucks are the D or W series

Bs are vans
Ds are 2 wheel drive pickups
Ws are 4 wheel drive pickups.

Thanks for the help you guys.
It is actually a 1978 dodge sportsman, don't know if it was a cut cab or cab and chassis. But started out as a van design.
The rear single axle with two wheels each side one inverted and covering the brake drum the other fitted the normal way around. That's my idea of a duely.
Most parts places on the internet have drawn a blank. But I did eventual get a reply from Napa with a list of parts. Now the daring question do they have them or can get them.
The rig is old but low mileage. The motor is a 360 4bl carb, A727 transmission and 4.10 rear end. If i've done my research correctly.
B300 series are supposed to fit according to the grape vine.