351/400M trans swap ??
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Senior User
Joined: Jan 2008
Posts: 165
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From: H/Lk. & S.E. Michigan
351/400M trans swap ??
I've got a 78' F-350 with a 4 speed granny trans and would like to swap it out for an 5 spd. O.D. Can anyone suggest the trans I can use to fit my engine ?
Or would I do just as well to change the rear gears. I'm hoping to improve my mileage so any suggestions are welcome.
The truck is in mint condition and I only have 12k on a complete rebuild at such time i had it set up to a 400 and love it, just would like better mileage possibly.
Does anyone know anything about these O.D. units that can be added to your existing trans?
Thanks for your input.
Or would I do just as well to change the rear gears. I'm hoping to improve my mileage so any suggestions are welcome.
The truck is in mint condition and I only have 12k on a complete rebuild at such time i had it set up to a 400 and love it, just would like better mileage possibly.
Does anyone know anything about these O.D. units that can be added to your existing trans?
Thanks for your input.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 783
From: Simi Valley, CA
You can spend a grand, you can spend ten grand to improve gas mileage, but you're wasting your money, because at best...you might add 2-3 Hwy MPG. Around town, the MPG will be the same.
These trucks have the aerodynamics of a brick. Gas was less than a buck a gallon when they were new, and back then no one gave a hoot about gas mileage.
All the money spent (not to mention the time and labor), will buy one heck of a lot of gasoline.
These trucks have the aerodynamics of a brick. Gas was less than a buck a gallon when they were new, and back then no one gave a hoot about gas mileage.
All the money spent (not to mention the time and labor), will buy one heck of a lot of gasoline.
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
Bought new, the Gear Vendors units will run between 2-3000, plus any driveshaft work. A 460 ZF will bolt to your 351M-400, but again, you will have to do some fabrication to get the driveshafts and the hydraulic clutch to work, plus you have to get a ZF from 91 and older to get a cable drive.
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