390 TRANS??

[JOSHR]

I have a 1972 F-250 Highboy the previous owner geared the rear end, so I get 50 miles an hour at about 3500 RPMs. I'm currently rebuilding the whole truck, body and everything. And I'm looking to convert from the 4 speed manual transmission that's in it. To a 5 speed. I heard about this NV4500, a gas Dodge transmission. But does transmissions don't sit well with me. Just looking for possible ideas and if anybody's ever use these 4500 Transmissions, feel free to inform me how it went

[Lee]

hi,

Do a search on "Overdrive" and you will see many posts on the subject. NV4500's, ZF's, Over-drive add-on adapters.

Lee

[1972hiboy]

Is re-gearing the rear end not an option?

[Canonman67]

While I don't have it on the road yet, the NV4500 is a bolt on with the adapter. Mine came out of a'98 Chevy diesel with 60,000 miles. I had to change the input shaft over to the Dodge but that was it as far as anything special. If you need more info I have quite a bit of it on the desktop at home. Everything I read was positive and up to this point my experience has been the same.

[rabbithunter2005]

I did a m5od swap on my 67 highboy. Unfortunately that wont work on your 390 neither will a zf5. I have heard those nv4500 transmissions are pretty strong a friend of mine is putting one in his 78f150 behind a 6bt. They are pricey tho. Gear vendors makes an overdrive unit but its about 2 grand I think. What gears were installed in your axles. Mine came with 4.56 gears from the factory I ended up getting a 4.10 high pinion Dana 44 up front and installed 4.10 gears in the rear. I run a 265 75 16 tire on mine. But even with the 5 speed transmission my inline 6 tops out at about 70mph down the interstate. I dont know my exact rpm cause my tach is a piece of crap it doesn't go higher than 2400rpm but it does sound like im still turning some high rpms. It is better than the old 4 speed was. I couldn't get above 60 before.