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Putting a 12V into my 04 F250
NV4500
NP271 Changed input shaft
Diesel Conversion motor mounts

Moved the motor all the way to the rear of the motor mount slot and rear driveshaft is going to be 3" short. Talked to Diesel Conversion and they say their mounts move the motor as far back as you can go before hitting the firewall (1" clearance). With the cab off tough to verify, anybody out there use their mounts?
If I can't move the motor back I'm left with question on whether to modify the driveshaft or convert to slip yoke. From what I read fixed yoke is stronger and has less vibration.
Another thought I have is to make a 3" spacer that bolts between the driveshaft and fixed yoke.

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Another photo.

 

I would find a different shaft to shorten, or re-tube the one you have. Losing the fixed yoke would be a mistake IMO.

What about moving the steady bearing mount forward? Is there extra travel in the rear slip yoke? Are you upgrading to bigger rear axle with a longer pinion? Just some ideas to consider....

 

Looks like I can only pick up a 1\2" moving the steady bearing closer. I am going to make a coupling to connect the fixed yoke and driveshaft. If that doesn't work it will cost $150 to get the driveshaft lengthened and balanced. Not planning on any rear end upgrades.

 

i would get it lengthened. i wouldnt chance it breaking and messing up the tcase

 

The guys at dieselpower did a little firewall mod to get the engine back a bit.

Custom Firewall Fill Plate Photo 10

Reason I asked about the rear diff.... the Dana 80 has a ~2" longer snout than a D70. I can only imagine the Ford 10.25" similar to the D70 in that respect.

 

Go get your driveshaft lengthened! Or call up someplace like Tom Woods custom driveshafts and have them make you one. I wouldnt start moving your motor back until you get the cab on, but I still doubt you will be able to move it enough to use that shaft and still have travel.