The Stovebolt Site Forums The Shop Area Driveline AD trucks - 3100 rear vs. 3600 rear

Hello!

Have been considering the purchase of an AD design truck to keep my '59 Apache company in the garage, and there seems to be a decent selection of AD trucks out there. My Apache is a 3600, so I know the gearing situation for these old trucks. It seems as if there are a TON of parts for 1/2 ton trucks, but much less for the 3/4 ton trucks. Do the 3100s and 3600 have different rear ends, or can you swap the pumpkin from a 3100 into a 3600? I ask because Patrick's offers 3:55 gears for the 1/2 ton, but nothing for the 3/4 ton, but it won't matter if the rear ends are the same.

Thanks...

Chris

3100 and 3600 rears are different, nothing interchanges. An AD 3600 will have the same rear that your '59 originally had which is the Eaton HO52, so you'll be in the same boat as you were with the Apache, which I think you put a Dana 60 in?

Steve -

Ok, I'm confused. The truck in question is a '51 3600, which I thought would have a torque tube rear end. The seller's description says that he replaced all the gaskets in the torque tube, so that's what he's got. Also, the seller says he replaced the original 4.56 carrier with a 4.11 carrier, so his rear end has to interchange with something.

The truck I'm referring to is the very nice original '51 3600 listed in the Trucks For Sale section, located in Minneapolis.

I really like the truck, but I don't want to buy a nice original vehicle only to have to completely replace most of the drivetrain to make it usable on modern roads. If I could get by with a gear swap, that would be enough.

Thanks...

Chris

On the Advance Design trucks, the 3/4 tons used a partial torque tube. The torque tube on those only went from the transmission to the carrier bearing, then from the carrier bearing back is an open drive like the 1 tons and your '59. The rear diff will be the same HO52 as the later 3/4 tons. The 4.11 3rd member that the seller mentions would have come from a '68-'72 3/4 ton, which is a direct interchange.

A stock '51, 3600 has the same rear housing as a 3800, that is, the Eaton HO52. It uses
an open drive shaft up to the center support bearing. From there it is the same
configuration as the 3100 closed drive shaft but not the same components.
All of the stock half ton rear axles are closed drive shaft all the way back to the rear axle
very much the same as the passenger cars of the same year.
If you keep the stock Eaton HO52 rear axle housing the best you can hope for is to find a
4.10 ratio center section from a late 60's to early 70's 3/4 ton. Other wise you will be
stuck with a 4.57 gear ratio in the 3600.
I have a 4.10 in my '50, 3604 and 50mph is very comfortable and easy on the engine but if
I have to it will run 55 to 60mph but it feels like I'm pushing the engine. It will run up to
65 or 70 but I'm afraid that a splash feed engine would not last to long at that speed before
it put a rod thru the block.

Denny Graham
Sandwich, IL

Ok, now I get it. Thanks to everyone for the clarification.

Based on what's being said here, I could do the exact same Dana 60 swap in this 3600 that I did on my '59 Apache 3600, am I right?

I ask because the Dana 60 swap I did was really pretty easy. The most involved part was widening the spring perches, which took me a few hours with a grinder and my mig welder. Other than that, it was pretty much a bolt-in operation.

Chris

I put a Dana 60 in my '53 3600.
The Dana was from a mid 60's F*&%$. Narrowest one I could find.3.73 gears.
Spring perches, shock mounts, U-joint/driveshaft shortened.
E-brake cables restructured.
Ford and Dodge 8-lug rears have a wider center than Chev.,so the Chev. wheels don't fit. Dana from a Chev would not have that problem, but they all seemed to be too wide.