The Stovebolt Site Forums The Shop Area Engine Shop Mazda rear swap? Your thoughts please

These gas prices are a killer in my 53 1 ton panel. Even though I've put in a T-5 and a a 4:10 pumpkin, I still am stuck at 15-16 mpg in town and about 17-18 0n the open road. I know that isn't too bad for what I'm driving but wonder if I could do better.
I have a rear end from an 89 Mazda B2000 that appears to fit but would it hold up to light highway and city conditions in a 1 ton panel? I would like some feed back on the strength of these rears. I know it is not a GM product but will save the original rear for that mythical future day when fuel prices are lower and I can go back to original. Also I'd like to put on 16' rims and tires to match the front which is original. Any thoughts? Will I loose braking power because of the smaller but more modern drums?

I wouldn't do it. I don't think you will gain much if any mileage. That truck is a brick in the wind, I think you should be very happy with 15 town / 18 hwy in a 1 ton vehicle.

Your T5 is the weak link right now, so a rear end built to handle a small truck with 120 hp might hold up. What gears are in that mazda rear? Usually the japanese truck rears are 4.10s behind a four cylinder.

What size tires are you running?

I don't think your t-5 is a problem but I bet your mileage would improve with a better ratio in the rear, say 3:42, which would still be stout enough for a load of wood or towing, but improve your high speed rpms.

I don't know much about those MAZDA rear ends other than that they were bought by FORD some years back. Whether it'll stand up under your panel depends on what you load into your panel, if you just drive it and put the kids/dog in the back, probably okay, if you are hauling bricks, maybe not.

It'll probably be easier and safter to find a replacement pumkin with better gearing.

What engine are you running?

I think your mileage is already fantastic! A 1-ton doing that good is something to celebrate!

I just bought a '50 1-ton frame and running gear from a guy who drove the truck for years, but has recently used the cab on another project.

He had swapped a later 14-bolt Chevy rear under it with 3.70 gears. His comment was that with the stock 216 that rear was just too high.

What motor do you have and what gears are in that Mazda? You might not be too happy with it after the swap.

Thanks for the replies! I guess I will be satisfied with what I have. As to the engine, it is a 261 that I rebuilt. It has an 848 head and is had been bored .080. I am running on 285/35/R16's. I have an HEI system with a Holley-Webber 2bbl; split manifold with dual pipes. According to the tach, it runs @1960rpm at 55mpg. You can see the truck in the gallery, 1953.