The Dana 44 is plenty strong. He also said he would not be taking her off road. I dont see an issue. In fact the Dana 44 came on 1 ton Chevys. In fact I suspect that is where he is getting his axles off of. The Dana 44 is a direct bolt in place of the Dana 60. The rear Corporate 14 FF may also be but most likely will need the perches moved in a few inches. That is easy. The shock mounts may need to be moved as well again easy. He could have all of these mods done and the axle mounted in less than an hour by himself. If the man wants to modify his truck then who are any of us to give him **** over it? Would any of you complain if some one changed from stock tires to Non original tires? No? Then why give him so much grief about swapping out axles so he can get the highway speed he wants without sacrificing his engine? Now that that has been said if you dont mind I will give you a few ideas I have kicked around for my M1028.
Changing the gear ratio in my stock axles. I am running 37" BFGoodrich Baja Mts on 12 bolt HMMWV wheels. I would like to run 75 (top speed) without grenading my engine.
37" tires 4.56 gears (stock)= 3105 RPM at 75 mph
37" tires 4.10 gears = 2792 RPM at 75 mph
37" tires 3.73 gears = 2540 RPM at 75 mph
Gear change cost about $700 bucks each axle. This does not include any traction devices.
Next idea:
Swap in a purpose built 700R4. This will give you an excellent OD .70 ratio and a lower first gear ratio 3.06:1
37" tires, 4.56 gears with .70 OD = 2174 rpms at 75 MPH (your engine is happy to run this all day)
Costs will run around $2500 for trans and swap and another $700 or so for your drive shafts to be shortened and lengthened. I would find a 700R4 that was built up. A stock 700R4 is not strong enough. DO NOT LISTEN TO PEOPLE WHO TELL YOU THEY CANT BE BUILT TO HANDLE EXTRA POWER AND TORQUE. They are stupid.
Option #3
37" tires, 4.56 gears, stock TH400 trans and a Gear Vendors unit= 2484 RPM at 75 MPH
You can find good used Gear Vendor units for about $800 if your willing to wait some time to find one. Right now you can find a bunch around $1,500 to $2,000. Craigs list is a good source as well as Ebay ect ect.
37" tires, 4.56 gears and Gear Vendors= 2484 RPMs at 75 MPH
37" tires, 4.10 gears and Gear Vendors= 2233 RPMs at 75 MPH
37" tires, 3.37 gears and Gear Vendors= 2032 RPMs ar 75 MPH
There are additional advantages to having a Gear Vendors unit. Its not just an Over Drive unit but also a Gear splitter!