ZF6 will bolt up. But then you have to figger out how to adapt the clutch, flywheel, and input shaft to match the ZF6.
As for the Tremec. If you have money to burn. I would contact them. You will most likely need adapters to bolt it behind a 6.5.
I would just stick with the NV 4500. It is a great transmission.

As for the heavy slow shifting. What trans oil are you using? NV 4500 requires their own special fluid. If not used. The synchros will wear out.
Never use regular gear oil in a NV 4500 it is not designed for it.

 

What trans oil are you using? NV 4500 requires their own special fluid. If not used. The synchros will wear out.
Never use regular gear oil in a NV 4500 it is not designed for it.

I know. Now I'm using Amsoil MTG 75-90. Its proper oil.
Maybe I'll try RedLine MT85. I used it before transmission rebuild.

 

Okay, one more question
The most difficult to engage is second and first gear. Is it normal? Or maybe there are a mistake in rebuild? Otherwise, the transmission is work properly.

 

NV 4500 should shift smoothly and easily.
If your rebuild used brass synchros, They can make a 4500 a little harder to shift than with the stock carbon fiber composite rings. Shifting usually improves as the synchros wear in.
Was the pilot bearing replaced? A worn pilot bearing will cause hard shifting.
Also clutch adjustment is critical in NV4500. The clutch must release fully for smooth shifts 1-2 shifts
Especially with the higher 1st gear ratio in the 93 4500s

 

AFAIK you have to use a synth GL-4 exclusively in the NV4500, like Castrol Syntorq or some other GL-4 synth fluid too, like maybe Ravenol.

Steve

 

The Tremec 4050 is basically an updated NV4500. However it's only available in the Dodge/ 96+ GM bellhousing transmission bolt pattern so it won't bolt up to your '93 bellhousing. I'd stick with the NV4500 given it's already been rebuilt and is a good transmission as is.

GM discontinued the transmission fluid for the NV4500 a year or two ago and from what I've heard the Amsoil fluid you're using is the recommended oil. Torque king sells the redline 85 for the NV4500, would be interesting to see if you notice any difference between fluids.

But if you're having hard shifting still it could be as already stated your clutch isn't completely disengaging. I had a similar problem on my '95 a few years back. Clutch pedal was so worn at the pivot point that it wasn't depressing the master cylinder fully and fully extending the throw of the slave cylinder. I had to make my own custom pushrod to get the clutch to fully disengage.

 

If its hard to grab gears, especially first and second, i'll bet good money that your clutch is not releasing properly. On a 93 there are shift blockers in those gears to prevent downshfting at speed, so if the clutch is dragging it can partially activate those. You need to make sure the hydraulics are a) in good working order and b) bled properly, and c) the fork and throwout bearing isn't worn. Does your truck have a pilot bearing or bushing? If it has a bearing, it might be dragging the input shaft.

With the engine off, is it easy to shift? if so, I would look at your clutch.

I have an NV in my '93. It has the torque king parts in it and I run Mt85 oil. I can shift every gear with one finger. However, my throwout bearing recently locked up and destroyed the fork and let me tell you, it was a bear to shift that. I thought the hydraulics were bad but after 2 sets in one week I knew something else was wrong. The NV is the smoothest shifting light transmission ever made. I wouldn't want to swap it out.

 

If your rebuild used brass synchros, They can make a 4500 a little harder to shift than with the stock carbon fiber composite rings.

I used composite rings from Torque King kit. I suppose this is the best rings for today.

Was the pilot bearing replaced?

Yes, pilot bearing is almost new, I replaced it a year ago then did a swap from 4L60E.

Also clutch adjustment is critical in NV4500.

I think the clutch has a proper ajustment. It engage the power in the middle of pedal stroke.
But i'll doublecheck this.

you have to use a synth GL-4 exclusively in the NV4500

Nope, GL4 is not enough. NV4500 needs a more special oil. This is a good note about it: CLICK

 

Nope, GL4 is not enough. NV4500 needs a more special oil. This is a good note about it: CLICK

I saw nothing in that link page that suggests that a synthetic GL-4 75w85 will not work. That's precisely what Castrol Syntorq was, and according to that doc you linked we now have Dodge dealers using ATF+4 as suitable replacement for their OE fills of Syntorq, which IMO is even more of a generic fluid that I would not be inclined to use. Half of the options listed on that link I would not consider.

What I posted originally was:

AFAIK you have to use a synth GL-4 exclusively in the NV4500, like Castrol Syntorq or some other GL-4 synth fluid too, like maybe Ravenol.

A synthetic GL-4 gear oil 75w85 will work. 75w90 would probably be fine too. There are several sources out there still with suitable fluid, but unless it's a synthetic and unless it has a GL-4 rating (MT1 is unacceptable) you should pass on it.

Steve

 

The Tremec 4050 is basically an updated NV4500.

A you shure? 4050 is very close to NV4500 by gears range, but the Tremec company seems dont has any common with New Venture.

However it's only available in the Dodge/ 96+ GM bellhousing transmission bolt pattern so it won't bolt up to your '93 bellhousing.

Thats true.

On a 93 there are shift blockers in those gears to prevent downshfting at speed

Oh, thats a point! Is a first gear have to engage only on stopped truck?

You need to make sure the hydraulics are a) in good working order and b) bled properly, and c) the fork and throwout bearing isn't worn. Does your truck have a pilot bearing or bushing? If it has a bearing, it might be dragging the input shaft.

I think all working properly. The master and slave cylinders, throwout bearing, pilot bearing - all is almost new, only 3k miles old.

With the engine off, is it easy to shift?

No, not easy, maybe a little easier.

I have an NV in my '93. It has the torque king parts in it and I run Mt85 oil. I can shift every gear with one finger.
The NV is the smoothest shifting light transmission ever made. I wouldn't want to swap it out.

Thanks for a feedback about NV. How many miles it?

 

Just a thought.
You may be on the right track switching over to Red Line MT85 oil.
IIRC it is lower viscosity than the Amsoil stuff. Beings MT 85 is a little thinner it may help to make easier shifting.
The Amsoil is a more of one size fits all oil. It is not exactly the same as the OEM Syntorque. But will work in NV 4500 without damaging the synchros.
From experience I like the Redline MT 85 in 4500s it has always worked well for me. It is very close to OEM Syntorque specs.

 

Before I rebuilt mine I did an experiment. Someone said that John Deere Hyguard meets the specs for the NV. I couldn't confirm that, but I was going to rebuild soon anyway. The MT85 and hyguard look the same. There is a slight difference in shift quality. The hyguard is worse, but not at all unbearable. Point being, oil does make a difference.

@randomsubfan I have about 50,000 miles on the rebuild. No problems.

I would still wager your clutch isn't working right. An easy test is as follows:

1: Truck running, clutch in, brake on, put shifter in 3rd
2: Keeping clutch in, move slowly from 3rd to neutral
3: wait a few seconds, continuing to hold the clutch
4: Holding the clutch, go slowly into reverse.

If there is any grinding going into reverse, the clutch isn't released all the way. A 93 has unsynchronized reverse, so if the internals of the trans are moving at all, it'll make noise going into reverse. Internals moving with clutch in= dragging clutch or pilot bearing. Just because you have new hydraulics doesn't mean anything. They are quite finicky and take some effort to bleed. Also with parts quality these days you might've got a dud.

First gear will engage while moving but on mine you need to be under 5-6 mph.

 

@randomsubfan by "updated" I do mean it's very similar in size and gear ratio and application. Main difference being an aluminum instead of cast iron case which some would consider an "update" or "upgrade" since being lighter makes it easier to install and remove. One difference that I don't like about the 4050 is that it has only 1 pto cover on the passenger side. I use the PTO cooling fins on my NV4500 which also have a spot for a temp probe. On my K3500 dump truck the hydraulic pump for the dump body bolts to the passenger side and still has the PTO cover on the other side for a cooling fin and temp probe. If using the 4050 I would be able to mount the pump but have no cooling fin/ temp probe option

@johnH123 I've never heard of the shift blockers, any link to what they look like or how they function? Not disputing their existence just something new to me. I'd like to know where they can be sourced from should I ever need to rebuild the original '93 trans in my k3500

@randomsubfan there is an inspection plug on the side of the bellhousing where the slave cylinder meets the fork. You can remove this plug and see how much throw/ travel the slave is making to determine if something is off mechanically with the clutch hydraulics. I went nuts a few years back with a dragging clutch, several slaves and master cylinders later (i.e. wasted money) I saw through the inspection cover that the slave cylinder wasn't moving to its full extent. Making a custom master cylinder pushrod solved the issue once and for all

 

@johnH123 I've never heard of the shift blockers, any link to what they look like or how they function? Not disputing their existence just something new to me. I'd like to know where they can be sourced from should I ever need to rebuild the original '93 trans in my k3500

Here is the part. Scroll down to read the tech notes.

QU10331 NV4500 1st and 2nd Gear Downshift Inhibitor Block

BLOCK, DOWNSHIFT INHIBITOR FOR EARLY PRODUCTION NV4500 5 SPEED TRANSMISSIONS QU10331

torqueking.com

Here is the section from the manual:

 

I would go zf6. From what I’ve gathered your already half way there already having hydraulic clutch