1985 F350 Transmission Options

I'm throwing my notes in here on the topic because I went through a lot of this putting my ZF5 and NP205 in my bullnose Bronco. I switched from a T170 4sp w/overdrive. Great little aluminum unit. Huge chasm between 2nd and 3rd, though. Had an NP208 also.

The twin stick controls on the NP205 unit require cutting into the ZF5 tailhousing. On the plus side... no adapter required. Zf5 is longer but NP205 is shorter so may require driveshafts. That NP205 is iron and weighs almost as much as the aluminum ZF5. They were never intended to be bolted together and the twisting force of the NP205 dangling off to the side may crack the tailhousing. You have to weld in a support to the frame rail and put a bushing in there to hold up the NP205, but does not require anything more than a couple of small stock steel plates. You can use the ZF5 boss to mount the controls for the NP205 too.

Having said that... WORTH IT!. Remember, I already had overdrive before, and switching to the ZF5 was like night and day. Mine has a granny gear and that makes a lot of the difference for me. I never use first unless I need to slowly climb a steep grade (or slowly maneuver my big-ass truck into anything narrow). Other than that, I leave stops in 2nd gear and it basically has 4 speeds for street use. I never run out of gear and get optimal RPM at 55-60 (just like a new car). I even mailed the shift tower off to Midwest and had them modify it for short-throw, which is really smooth and quick.

Maybe a ZF5 isn't right for your application, but it can't hurt to keep your eye out for them. I see S5-42 for SBF occasionally on Facebook Marketplace. If you see one, I wouldn't be afraid to snag it. The SBF/BBF/IDI units all use the EXACT SAME INSIDES AND TAILHOUSINGS (excluding the S5-47 units which are only interchangeable between other S5-47 units, but good luck finding one of those). The only thing that is unique between them is the case, so if you buy one make sure the case is good and you can replace anything else fairly easily if it's worn (meaning parts are available). Remember, there is a reason that the ZF5s are hard to find: it's because they are great transmissions. I'm not throwing any shade on the other options, but I really like my ZF5 and it has no issue with the 500+ hp I'm pushing through it.

Have fun with your build!

That is an excellent point about the NP205 mount. From the factory they had their own support. I would not hang one off of an aluminum transmission without fabricating a cross member for it. The ZF 4x4 already has a known cracking problem in the rear case webbing.

I've got a lead on a couple T19s to rebuild.  One of them does not come with the shift lever.

I'm finding conflicting opinions on if I could use my T18 shift handle with a T19.  Anyone know for sure?

I can't answer the question, but would have thought that I should be able to.  

I looked in the master parts catalog and got the generic part number for the shift lever, which is 7210.  Then I went to the application listing and found that T18's use parts list #'s like 4E and 4J while T18's are 4D, 4H, etc.  Then I went to the parts list and discovered that it doesn't include 7210.  So I can't help.  Sorry.  

BabeTheBlueOx wrote

I've got a lead on a couple T19s to rebuild.  One of them does not come with the shift lever.

I'm finding conflicting opinions on if I could use my T18 shift handle with a T19.  Anyone know for sure?

I can get you pictures of my T19 shift handle with measurements.

The only thing I'd be concerned about is the length and shape of the bottom end because the lids are different on both gearboxes.

My T18 shifter did NOT fit my T19. I wanted an old style shifter cane with a thread-on knob. I eventually found one that fit, but it did not shift as smoothly as the original so I changed back to the original.

The issue (as pointed out by another member already) is the length of the stub that mates with the shift forks. My T18 shifter stub was considerably longer than the T19 out of my diesel.

I don’t know if this helps, but my T19 stub stick-out is 3 1/16” from the bottom of the pivot to the tip of the stub:


The pivot is separate but not readily moveable. It seems to be pressed on, or one heated and one cooled like a gear on a shaft.

Thanks for all the great information!

Here's where I'm at.  I got my hands on a later-model NP435 that's in good shape.  It shifts very easy; I'm going to crack it open this weekend and see what I see.

I've driven 7+ hours over the last two weeks chasing a T19, and honestly, I'm kind of over it.  Plus I've read some opinions that the NP is the easiest shifting of the old 4 speeds, so I might just drop the synchro'd 1st gear dream and go with the NP.

I'd value any experience and opinions contrasting the T19 and NP.

I've had both and rarely had to shift into 1st while rolling at any speed at all, so the lack of synchros on the NP didn't bother me.  And if you do any offroading the NP's 6.69 first beats the 5.11 first of the T19.

I too, have had and owned both. The NP435 that I had was rode hard and put away wet. Finding that elusive third gear notch in the sea of slop wasn’t even repeatable enough to learn, and downshifting required double clutching and very good timing skills. So my specimen was shot. I don’t blame the make and model, if you find a good one I hear they can shift beautifully. My only other complaint does have to do with design. It has the worst gap from 3rd to 4th of any of the granny 4 speeds. It probably isn’t as bad paired with a faster revving V8 with a broader power band, but with low rpm straight sixes it’s a real drag. The 5.11 and 6.32 versions of the T19 are not much different though. I would say absolutely go for it if you know it shifts well.