69 4x4 with manual

[sparky 69 3/4 ton]

I would like to find a different transmission for my 69 3/4 ton 4x4. The stock transmission is a manual 4 speed. I would like to convert to something with overdrive for the highway. Any suggestions would be appreciated

[propanemudtruck]

Are you planning to stay manual? There is the NV3500 and NV4500, or 700R4 Auto, 4L60E Auto, 4L80E Auto... quite a few options you might have.

[sparky 69 3/4 ton]

I will probably stay with the manual unless I can go to an automatic and keep the shifter on the floor. I dont want to patch a hole in the floor and change the steering column

[sdailey]

The most common swap is for a NV4500. There are a few folks on here that have documented the swap in their build threads. You should be able to search "nv4500" and find some useful info.

[special-K]

Just bear in mind the overdrive manuals won`t be as tough as a good ole 4spd.I`ve been through three NV4500 that weren`t wheeled hard,if at all.I`ve never had a 4spd fail.

[martindc1]

The best thing I did for highway rpms was a muffler lol.

Maybe you could also look into an overdrive unit. It would probably be a wash money wise versus getting a nv4500 and all the necessary parts.

If you didn't want to put one on the back or your transfer case, I saw on another thread that somebody with a 60-66 put one between their transmission and the divorced transfer case. If you wanted to go that route you could find a 2wd sm465 and a divorced np205 from an old Dodge. I've seen a few 2wd sm465s for next to nothing.

[Chevymaniac]

Originally Posted by special-K

Just bear in mind the overdrive manuals won`t be as tough as a good ole 4spd.I`ve been through three NV4500 that weren`t wheeled hard,if at all.I`ve never had a 4spd fail.

So what makes the NV4500 such a weak tranny compared to 4spd?
I thought about doing a swap like this myself. Is the NV5600 a good replacement?

[andyh1956]

the nv 4500 is built like an oversize toyota or asian / warner 5 spd- with the od gear in the rear of the trans under the output shaft. there are stronger trans out there, ilke the clark. however i own two nv 4500 and have worked the dog snot out of them with good results. now o/d is expensive unless your rich aunty gives you one. advance adapters markets what they call the "ranger" o/d- it fits between your clutch housing & the front of your trans- sorta a "sandwich" deal. that way you could keep your 465 muncie with just shorten / lengthen your driveshafts & moving trans crossmember back. good luck!
andy

[sparky 69 3/4 ton]

Where would I find out what transmission I have? Was a Muncie 4 speed the only manual available in a 69 3/4 ton? I like the idea of keeping the stock transmission and just adding overdrive. The truck only has 9000 original miles so I hate to spend the money on a whole new transmission if I can make the one I have work. Thanks for all the input!!

[Mike C]

A trans swap may not be your easiest way to get RPM down based on your questions. What other goals do you have for the truck? Number 1, how much money do you want to spend? How much wrenching experience do you have?

A gear swap would probably be cheaper than an NV4500 conversion, especially if you can find a later model parts truck. You need to know what gear you have, and if it's 4.57 a later 73-87 3/4 ton truck would have 4.10 most common and in a Suburban 3/4 ton 3.73. I paid $200 for the last Suburban parts truck I got with 3.73 semi-float in the back and 10 bolt in the front. I paid $300 for one with 4:10. Nice thing about this swap is you get disc brakes as well.

What size tire do you have now? Do you have plans to put on a lift and big tires? 37's and an SM465 (your trans) work pretty well with 4.57. If you have 4.10's, 35's work pretty well.

Figure out where you want to go suspension, tire, motor wise and how much money you want to spend. THEN figure out what the best way to get there is.

[1969 GMC]

Originally Posted by Chevymaniac

So what makes the NV4500 such a weak tranny compared to 4spd?
I thought about doing a swap like this myself. Is the NV5600 a good replacement?

the dodge cummins guys have lots of problems with the NV5600, but then again, they are running a cummins. however, they only used it for a few years so if you find one that isn't grenaded, and is somewhat reasonably priced, you will still have to figure out how to adapt it to a chevy motor. the 5600 has an integral bellhousing unlike the 4500.

however the zf6 from newer chevy trucks could work...

also, there is the ranger overdrive from advance adapters.
http://advanceadapters.com/product/1941/760002M-27.html
it goes in between the bell and tranny, and is basically a 2 speed range box, with direct and either under or overdrive. the overdrive is .73, just like 5th gear in a nv4500, and would allow you to use the stock tranny, just have to move everything back a few inches, maybe redo drivelines. and you would be able to split all 4+R gears, effectively giving you 8 forward speeds and 2 reverses.

[duallyjams]

69 4x4 came with sm465 and a rockwell transfer case.If you go with a nv4500 you will have to up grade to a np205 transfer case.It would be cheaper to change your gear ratio then to do a nv4500 conversion.A up graded built nv4500 that is bullet prof will run around 3,000 and that does not include the bell housing or hydraulic clutch swap.

[sparky 69 3/4 ton]

It sounds like my best option will be to change the gears around. I am planning either a 4 inch or 6 inch lift. I would like to run 35's. The other options sound like they are a little out of my wrenching capabilities. I am pretty new to this. I can handle the basics but anything too advanced is a little out of my reach at this point. Thanks again for everybodys help.

[martindc1]

Depends on what gears you have. I'm guessing you have an HO52 rear with 4.57 gears. These have a removable "pig" which means the center section holding the pinion gear and differential unbolts from the housing. You could try to find a 4.10 pig, then you'd just have to change your front axle gears.

Another option, as stated above, would be to find a matching set of 4.10 or 3.73 axles from a later truck. Honestly, this is probably your least expensive option. However, there you may have to get the master cylinder from the later truck as well since you would be changing over to the later disk brakes.

[Mike C]

Do the brakes. The drums are marginal with stock tires and unacceptable with 35's IMO. But, with 35's you may find the 4.57 are not so difficult. I would do the lift/tires first while doing the disc swap. You should be able to swap outers from a later axle on your open knuckle stock axle.