What if anything could I swap out for to make my '73 360 Np435 Np201 F9" 4x4 useful for towing a boat at highway speeds?

 

Well I only have a fundamental question on that--what's wrong with it as is? The 360 should pack enough punch to do the job. You probably have a 3.73 rear end so that would give you at least 65 mph without the engine yelling at you too much. I just did a tow job with my '77 (351M, 4 speed with 3.50 rears) and I was very happy with it. No struggle, no swaying and no lack of power.

 

OH, I see you're from Tempe, AZ. I am from Phoenix but haven't lived there in many years.

 

I guess I may need to see what gears I have. Just went from 31s to 35s still doesn't seem happy much over 55. Does a Np205 hi gear over drive? I think the Np201 is straight thru?

 

NP205 is straight through 1:1.

 

I would swap in a nv4500. I swapped one in behind my 390 and it is probably my favorite mod in my 76.

 

Ya sounds to me like your looking for a overdrive to keep the rpm down at highway speeds. Many people here have done it. Just not me. Lol. Good luck.

 

Here is an awesome write up to look at that describes the nv4500 swap in great detail.
Installing the NV4500 Overdrive Transmission - Ford-Trucks.com


For mine since I have a highboy with the divorced case I just used a 2wd nv4500 tranny and made a custom shift lever bracket to bolt onto it. This is a pretty much bolt in swap short of the tranny mount.

 

I take it you're running 4.10 or so? 3.73 gears would be great or a separate overdrive unit

 

Great write up on the Nv4500. Sounds like a great option. Any others?