I am about to buy a 77 F250 4x4 highboy that is a one owner farm truck and I am having a hard time trying to find websites, other than this one, to get info on that year of truck. I know that the truck I am getting originally had a 400. It also has a 4 speed tranmission but I am not sure if it is a T-18 or a NP 435. Which one is better to have and how much horsepower/torque can a manual transmission handle? I am currently having a 400 stroker built, will be 434 cu in when all done. I have heard that it is good to convert the power steering to that of a 78/79 truck. Does anyone have any good info or suggestions? Thanks!

 

Did you read the Read first: threads on the top of the list in this forum ?

The Highboy is explained in there.

 

I think either the T-18 or NP435 would handle much more power than what the engine will be pushing...as long as the tranny itself is not about to take a dump already. Don't underestimate those old granny trannys. Though the ZF five speed or NV4500 would be a nice thing to have (OD). Personally I would like the 6 speed that comes behind the Power Strokes.

 

A T18 is all cast iron a 435 has a aluminum top cap where your shifter is.

 

Are you sure it's a highboy? '77 was a split year, early ones were highboys, later ones were not. Does it have a divorced transfer case? Does it have any power steering on it at all? The 78-79 integral p/s system is the best.

T18 has reverse to the right and up toward dash. NP435 has reverse to the right and down toward seat. Both are great trannys - very tough.

Marty

 

How does one differentiate between a T18 and NP435 on a visual basis ?? Where are the ID #s etc ??

 

"highboy's" did not come with 400's.

Both the t-18 and the 435 had reverse going to the right and towords the seat.

There is a tag between two bolts on the side cover plate on the tranny. This will give the tranny info. Some tags might be connected with just one bolt, but usually they span between 2.

There really is no strength difference between the 2.

 

It actually had a 351M originally but there is not much of a difference and I will be putting a 434 (stroked 400) cu in engine in it.

 

Ok, I'll rephrase it, "high boy's" didn't come with 335 series motors. 300I6, 302, 360 only. And I might be wrong about the 302.

It could have been transplanted in somewhere along the line, but it's not factory, if it's a "high boy".

Is the transfer case connected to the transmission, or is it back a few inches, with a little driveshaft in between the tranny and transfer case??? If the tranny and transfer case are bolted together, then you don't have a "high boy" and you already have the newer PS.

 

You could get a 77' Highboy with a 400. I own one.

 

In '77 Ford redesigned the chassis. When the chassis was introduced, so was a new line of motors in the trucks, the 335 series. These were introduced in response to the push for emissions systems on trucks. The 335 series was designed and built from the start for emissions. The motor and chassis were released at the same time. While I suppose it is possible someone ordered a new motor in the older chassis, I find it hard to believe Ford would do it. But I suppose, anything for a buck. Have you ran the codes to verify that the factory codes show a 400 as the installed motor from the factory???

 

My engine code is H which is a 351M which is a 335 series engine that was factory and my truck was built in 12/76 as a 77 model.

 

And it'a a "high boy" with a 400, divorced t-case, and 2 1/2 wide springs??? Hmmm VERY rare truck indeed. I bet there is less than a couple hundered made...if that. Collectors Item??? I would love to find a truck like that to put a 460 in and a D70 out back and make it into a 4x4DRW instead of doing it to an older FE motored one.

 

I don' know how rare it is...my VIN is F26HR080517 it had the 351M, 4 spd NP-435 transmission, divorced NP205 and 2 1/2 in wide springs, 4 in block under the rear springs, Dana 44 in front and a Dana 60 in back with an in cab gas tank, 100 MPH speedometer... just a good F250 highboy!

 

Ford didn't change the chassis until mid year (5/77). Not hardly rare, lots of "late" highboys running around with 400/351m's, divorced transfers and in my case Dana 70 in the rear HD Dana 44 in the front, 2.5 springs (mine has 9 in front 14 in rear). Most of the late ones also had beds with gas tank ports, BUT still had the tanks in the cab, Tricky part here is that the "ports" are blanks and can not be opened. My code does state a 400/c-6 combo from factory. Good luck on putting a 460 in that narrow frame, it can be done but its not exactly a drop in deal, I looked at doing it (because I just happen to have a "spare" 460/C-6) BUT figured it was WAY more work then I wanted to put into the truck.