NV4500 swap installed and rollin!

[kipps]

Originally Posted by yfs200p

I know this is somewhat of an old thread, but can you confirm this? I have an 89 v30 with SM465 (shot) and NP205. I would love to swap to an NV4500 instead of rebuilding the sm465. I’ve read a bunch about it, but a little confused. How can I make them the same length, swap input shaft on the Tcase, put an adapter between them, both? I would love to leave Tcase in the factory position and not mess with driveshaft lengths. Thanks!

I've never worked with, or researched, a np205. I don't know much about how they vary from the np208 in fitment. post #6 of the following link indicates that sm465-fitted 85-91 np205 are interchangeable with the sm465-fitted np208 cases. Also, the np241 and np208 are identical in fitment. By correlation, the 85-91 np205 "should" fit in place of the np241 which came behind the nv4500 from the factory.

https://www.pirate4x4.com/threads/sm...-np205.519198/

It appears you have one of the rare desirable 32-spline np205 cases with the round six-bolt pattern.

A nv4500 is virtually the same length as a sm465, if both are 4wd. There are slight differences of less than 1/2 an inch, but as far as I know, that's just manufacturing discrepancies over the years. It's not enough to cause any issue with driveshafts.

A potential issue is the transfer case shift linkage. The nv4500 never had the connection point for the transfer case shift linkage that the np205 requires. You'll need to fab up a bracket, or buy one. It appears that Advance Adapters makes, or did make, a bracket for that purpose.

Edit to add: be sure to look over any nv4500 good before installing it. Ideally even before buying it. Remove the shift cover, the pto plates, and the rear extension housing. Look for any debris in the oil, check for excessive slop in the input shaft/mainshaft combo, make sure there are no chipped or badly worn gear teeth, and confirm that the fifth gear nut and gear are still in their correct locations. It's also possible to tell the general condition of the synchros, just by looking at the spacing between the sychro teeth and the engagement teeth. I'm not well versed on that, though. I bought a 1997 nv4500 sight-unseen, and intended to stab it in and run it as-is. I opened it up, and found that fifth gear was half-way backed off, the input shaft thrust bearing was gone, the 3/4 synchro hub was trashed because of that missing bearing, the parts of that bearing had chipped two gear teeth, and the synchros were heavily worn. I'm facing $1000 in parts to get this thing back in operable condition. If I had run it as-is, it most certainly would have failed in the first 100 miles. These nv4500's are not hard to work on, if you have access to bearing pullers, a press, and basic fabrication tools for making some of the specialty tools required.

[SunSoaked]

Originally Posted by kipps

I've never worked with, or researched, a np205. I don't know much about how they vary from the np208 in fitment. post #6 of the following link indicates that sm465-fitted 85-91 np205 are interchangeable with the sm465-fitted np208 cases. Also, the np241 and np208 are identical in fitment. By correlation, the 85-91 np205 "should" fit in place of the np241 which came behind the nv4500 from the factory.

https://www.pirate4x4.com/threads/sm...-np205.519198/

It appears you have one of the rare desirable 32-spline np205 cases with the round six-bolt pattern.

A nv4500 is virtually the same length as a sm465, if both are 4wd. There are slight differences of less than 1/2 an inch, but as far as I know, that's just manufacturing discrepancies over the years. It's not enough to cause any issue with driveshafts.

A potential issue is the transfer case shift linkage. The nv4500 never had the connection point for the transfer case shift linkage that the np205 requires. You'll need to fab up a bracket, or buy one. It appears that Advance Adapters makes, or did make, a bracket for that purpose.

Edit to add: be sure to look over any nv4500 good before installing it. Ideally even before buying it. Remove the shift cover, the pto plates, and the rear extension housing. Look for any debris in the oil, check for excessive slop in the input shaft/mainshaft combo, make sure there are no chipped or badly worn gear teeth, and confirm that the fifth gear nut and gear are still in their correct locations. It's also possible to tell the general condition of the synchros, just by looking at the spacing between the sychro teeth and the engagement teeth. I'm not well versed on that, though. I bought a 1997 nv4500 sight-unseen, and intended to stab it in and run it as-is. I opened it up, and found that fifth gear was half-way backed off, the input shaft thrust bearing was gone, the 3/4 synchro hub was trashed because of that missing bearing, the parts of that bearing had chipped two gear teeth, and the synchros were heavily worn. I'm facing $1000 in parts to get this thing back in operable condition. If I had run it as-is, it most certainly would have failed in the first 100 miles. These nv4500's are not hard to work on, if you have access to bearing pullers, a press, and basic fabrication tools for making some of the specialty tools required.

$1000 in parts? I'm fixing to rebuild my spare nv4500 at about half that price from Allstate. I wouldn't buy a used trans without assuming it needs rebuilt. Although I got lucky on my current one I just installed but I was able to drive the donor truck before he pulled it.

[doubleclucker]

Originally Posted by yfs200p

I know this is somewhat of an old thread, but can you confirm this? I have an 89 v30 with SM465 (shot) and NP205. I would love to swap to an NV4500 instead of rebuilding the sm465. I’ve read a bunch about it, but a little confused. How can I make them the same length, swap input shaft on the Tcase, put an adapter between them, both? I would love to leave Tcase in the factory position and not mess with driveshaft lengths. Thanks!

I have been there and done this on my thread and had 1.5" longer than what I had before . though i took out a sm465 /bathtub np205 and replaced it with nv4500/round pattern 205 with short input swap.

[kipps]

Originally Posted by doubleclucker

I have been there and done this on my thread and you will have 1.5" longer than what you have now .
https://67-72chevytrucks.com/vboard/...d.php?t=611566

https://67-72chevytrucks.com/vboard/...d.php?t=611566

I just read through your build thread. It's awesome!

Are you sure the extra 1.5 of length didn't show up in the t-case swap? I've had my hands on three transmissions simultaneously; a 4wd sm465 with the factory hydraulic bell, a 1993 4wd nv4500 with the factory external slave bell, and a 1997 4wd nv4500 with the factory internal slave bell. All three measured within a half inch of length from the engine block to the transfer case mating surface. The trans mount point was the same as well.

[1976gmc20]

The sm465 got a different bellhousing(passenger side external slave) and an aluminum shift cover with a more rearward shift position, when it was installed in the gmt400 trucks. The rest of the transmission remained exactly the same as the one used in the 87-91 R/V trucks. When the sm465 was swapped out in the middle of the model run for the nv3500/nv4500, those two transmissions were sized to fit exactly in the vacated space.

So ... does that mean an SM465 would just drop into a 1989 GMT400 with the NV3500 ?

(I know you're asking "Why?" but I use it more off-road than on the highway so the granny gear would be more useful than the overdrive)

[kipps]

Originally Posted by 1976gmc20

So ... does that mean an SM465 would just drop into a 1989 GMT400 with the NV3500 ?

(I know you're asking "Why?" but I use it more off-road than on the highway so the granny gear would be more useful than the overdrive)

If you can find an aluminum-top sm465, yes. The aluminum tops had the rearward shift position and the low passenger side slave. You'll want to definitely get the correct bellhousing to go with this sm465.

The squarebody iron-tops will need floor modifications, custom slave cylinder plumbing, and possibly exhaust rerouting to clear the slave.

Also look for the 1992-1994 nv4500. These years had the granny gear and the overdrive. The granny isn't quite as deep as the sm465, but it's close. These should drop right in, but you might have to change the transfer case input shaft. Again, you'll want to purchase an nv4500 complete with a bellhousing.

I might be winging it a bit here. I'm confident in my information regarding the nv4500. I'm less certain about my knowledge of the nv3500. Keep that in mind with the following paragraph.

The R/V trucks continued to offer the iron-top sm465 as the only manual option through the end of their run in 1991. The gmt400 trucks started out with the nv3500 in 1988 on the half-tons. The heavier trucks got the aluminum-top sm465's with the rearward shift position and passenger side slave. This shift position and slave position were identical to the nv3500. In 1992, the sm465 was dropped for good, and the nv4500 showed up on the scene. This was the same length, the same shift position, and the same slave position as the lighter nv3500 and the now-discontinued aluminum-top sm465. My knowledge of the nv3500 drops out at this point. The nv4500 continued in the granny-low configuration through 1994. In 1995, it was rearranged to match the Dodge nv4500 ratios. Granny low was dropped, and all the gears were spaced better for daily driving. In 1996, the bellhousing to trans bolt pattern was changed to match the dodge bolt pattern. At the same time, a new internal slave bellhousing was introduced. A few more minor changes followed in 1997 and 2001, but those don't affect fitment much.

In summary, any manual transmission from a gmt400 should be interchangeable with any other, until you get into the mid-90's with the internal slaves. The aluminum-top sm465, the nv3500, and the nv4500 can all be switched. Just make sure each one comes with it's respective bellhousing. The bellhousing has to stay with the respective transmission. Also, the spline counts on the t-case input shaft might change between the lighter weight trucks and the heavy weights. The input shaft on a np241 is a very easy and cheap swap, though.

[1976gmc20]

Okay, thanks!

That tells me just any old 465 won't fit; has to be from a GMT400. So I will just go back to my original plan: eventually try to find a decent 73-87 K/20 with an SM465 for my "ranch" truck.

I get pretty tired of putting the 89 K1500 in low range any time I need to back up a little hill, or do anything slow and careful