NP435 swap
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5th Wheeling
Joined: May 2013
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NP435 swap
I recently bought a 1964 F250. The previous owner swapped in a 360 with an NP435. I've had it for only a couple months and it's been great, but I just lost 2nd and 3rd gear. As much as I like the np435 I top out at about 45mph, so I'd like to swap it for something that will provide a bit more drivability. Any suggestions? I should add that the rear end is spicer/Dana 4.10 and I plan on doing a bit of heavy towing. Any tips or input would be great. Thanks guys!
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5th Wheeling
Joined: May 2013
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Hmm that's a good question then. There's no tach but but the rpms past 45 are really high.. If I really push it I might get 50, but it's maxed there.
I wouldn't be opposed to rebuilding the 435 if I could get a decent highway speed.
I wouldn't be opposed to rebuilding the 435 if I could get a decent highway speed.
Laughing Gas
Joined: Dec 2010
Posts: 1,091
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From: Tucson, Arizona
Since you're talking about a nearly 50 year old truck which no longer has its original engine, maybe the differential gears were also swapped out to, say, 4.56s? Are you sure your speedo is accurate? Tachs don't cost much and are easy to hook up - then you'll know what you're really turning. Someone may correct me, but I think stock 360 2 bbls are pretty much done winding by about 4800 - 5000. Too bad you don't live in Arizona - I have a surplus NP435 available. Good luck!
Logistics Pro
Joined: Feb 2011
Posts: 3,522
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From: Townsend, MT
And if you wind them that high in 4th with 4.10's you'll be over 100.
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5th Wheeling
Joined: May 2013
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So if the rebuild doesn't solve the prob then there is another issue that ill need to address regardless of which trans I have in there.
Thanks for all the quick responses I appreciate the help
Chad
Thanks for all the quick responses I appreciate the help
Chad
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Joined: Apr 2013
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why would it ruin the mileage? im new at this and have no idea what im doing. but i also have am np 435 that id like to put a tremec 5 speed in its place. however i dont know what gears ive got. theres no id plate on my diff that i can find. and i have a 390 in it and no tach but it sounds high rpms above 45.
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why would it ruin the mileage? im new at this and have no idea what im doing. but i also have am np 435 that id like to put a tremec 5 speed in its place. however i dont know what gears ive got. theres no id plate on my diff that i can find. and i have a 390 in it and no tach but it sounds high rpms above 45.
F100 9" ID tag located at approx. 5 o'clock under one of the bolts that retains carrier to housing.
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5th Wheeling
Joined: May 2013
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Thanks for everyone's input on the 435. I know it's been awhile now but I wanted to give some resolution. I ended up rebuilding the np435 I had. The synchro was dust- literally pulverized like mud in the bottom of the trans. The problem with the high rpms at low speed was a problem with the transfer case. I was able to move the shifter but it was never actually coming out of 4 low.
Thanks for all the help
Thanks for all the help
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