Replacing transfer-case with divorced 205 install help

[79 oshkosh 2323]

This 724 has a 6BT with a automatic transmission, It still has the divorced 200 transfercase. Would like to install a 205 divorced transfercase. Is anything as far as mounting brackets the same.. Sorry for the misunderstanding . I have a hard time explaining things sometimes

 

[Barrman]

I read your post several times and am still confused. You have a 6BT with an automatic in your truck already? If so, then getting a 4 wheel drive automatic and a married NP205 might be your best option. Just a single crossmember for the transmission and transfer case that way.

Everything else being stock going to a NP205 is not that bad but there are a few issues:

U-joint yokes. I think the Dodge version has the same spline count as the NP200 so you can just unbolt and swap them around for a plug and play kind of thing. Otherwise conversion u-joints, expensive yokes or new drive shafts will all have to be figured out and made.

Parking brake. There is no provision on the stock M715 for parking brakes in the axles. Only the transfer case mounted one realistically works. You can take the housing off the NP200 that holds the parking brake, along with the output housing off the NP205 to someone with a lathe/mill and they can cut a very small groove into the NP200 part so it can bolt to the NP205 and then you have a parking brake.

Mounting. The stock NP200 brackets do not bolt to a NP205. You will have to make your own. Some people use the stock cross members and go from there while others just make everything from scratch. There are pictures on this site and the M715 zone of this.

Shift linkage. The NP205 was made for a single shifter. The M715 has 2 shifters for the transfer case. You can remove the shift rails from a NP205 and by cutting small groves at specific points make it a twin stick unit. Searching for NP205 twin stick conversion will tell you all about that.

Finally, I have to ask. Why do you want a NP205? Same low range ratio, same basic case and same basic strength. The only real downside to a NP200 is the whine in a M715 which can be eliminated by doing a center output conversion and the heat created above 48 mph on stock tires for at least 45 minutes of highway cruising. The NP200 is actually sought after by extreme off road rock crawler types because it can be clocked almost straight down for the output shafts.

 

[79 oshkosh 2323]

I read your post several times and am still confused. You have a 6BT with an automatic in your truck already? If so, then getting a 4 wheel drive automatic and a married NP205 might be your best option. Just a single crossmember for the transmission and transfer case that way.

Everything else being stock going to a NP205 is not that bad but there are a few issues:

U-joint yokes. I think the Dodge version has the same spline count as the NP200 so you can just unbolt and swap them around for a plug and play kind of thing. Otherwise conversion u-joints, expensive yokes or new drive shafts will all have to be figured out and made.

Parking brake. There is no provision on the stock M715 for parking brakes in the axles. Only the transfer case mounted one realistically works. You can take the housing off the NP200 that holds the parking brake, along with the output housing off the NP205 to someone with a lathe/mill and they can cut a very small groove into the NP200 part so it can bolt to the NP205 and then you have a parking brake.

Mounting. The stock NP200 brackets do not bolt to a NP205. You will have to make your own. Some people use the stock cross members and go from there while others just make everything from scratch. There are pictures on this site and the M715 zone of this.

Shift linkage. The NP205 was made for a single shifter. The M715 has 2 shifters for the transfer case. You can remove the shift rails from a NP205 and by cutting small groves at specific points make it a twin stick unit. Searching for NP205 twin stick conversion will tell you all about that.

Finally, I have to ask. Why do you want a NP205? Same low range ratio, same basic case and same basic strength. The only real downside to a NP200 is the whine in a M715 which can be eliminated by doing a center output conversion and the heat created above 48 mph on stock tires for at least 45 minutes of highway cruising. The NP200 is actually sought after by extreme off road rock crawler types because it can be clocked almost straight down for the output shafts.

Sorry for the confusion . Some times i cant put into words what i would like to say.. .. i was told the 205 was better.. Is putting the drive shaft in the center yolk where the brake is the way to go and leave the 200 in there.. . Im new to the M715 -M724 trucks

 

[Barrman]

The NP200 heat issue gets argued and debated on the M715 zone just about annually. The best I can figure. About 20%-30% can run all day with the engine at redline and have no problems. The rest can’t handle more than 2500 rpm drive shaft speed for more than about 45 minutes before they get extremely hot.

Putting a yoke on the parking brake output and driving the rear drive shaft from there completely eliminates the whine and fixes the heating issue in another 20% or so of the cases. I did that conversion on mine and love not having any whine.

However, mine still gets hot. So, I am in the other 50% that has heat issues. When I put the big block 396/NV4500 in mine I changed the NP200 to synthetic Mobile 1 gear oil. I was cruising along at 65 mph with the top off and after about 45 minutes I started smelling something burning. I pulled over and my digital thermometer said 285° on the transfer case case and climbing. I got back in and continued at 52 mph which is right at 2500 drive shaft rpm with my 11.00 XZL tires. 30 minutes later it was below 200°.

I started looking for a divorced NP205 I could afford. Finally finding one a year or so later. I got the brake bracket machined and using a spare stock cross member made mounts for it. My Chevy NP205 has different spline counts than the NP200. The last time I looked it was going to be around $500 for just yokes. Around that time my big block broke and I put a 6.2 diesel in the truck. It can pull the truck at fast speeds but not like the big block. 48-52 mph are just fine for the diesel and I lost interest in swapping the NP200 out.

The center output conversion is basically installing M37 parts on the NP200 since the M37 is what the NP200 was designed for. Vintage Power Wagons is where I got my kit from decades ago. I have no idea if they still have any.

 

[79 oshkosh 2323]

The NP200 heat issue gets argued and debated on the M715 zone just about annually. The best I can figure. About 20%-30% can run all day with the engine at redline and have no problems. The rest can’t handle more than 2500 rpm drive shaft speed for more than about 45 minutes before they get extremely hot.

Putting a yoke on the parking brake output and driving the rear drive shaft from there completely eliminates the whine and fixes the heating issue in another 20% or so of the cases. I did that conversion on mine and love not having any whine.

However, mine still gets hot. So, I am in the other 50% that has heat issues. When I put the big block 396/NV4500 in mine I changed the NP200 to synthetic Mobile 1 gear oil. I was cruising along at 65 mph with the top off and after about 45 minutes I started smelling something burning. I pulled over and my digital thermometer said 285° on the transfer case case and climbing. I got back in and continued at 52 mph which is right at 2500 drive shaft rpm with my 11.00 XZL tires. 30 minutes later it was below 200°.

I started looking for a divorced NP205 I could afford. Finally finding one a year or so later. I got the brake bracket machined and using a spare stock cross member made mounts for it. My Chevy NP205 has different spline counts than the NP200. The last time I looked it was going to be around $500 for just yokes. Around that time my big block broke and I put a 6.2 diesel in the truck. It can pull the truck at fast speeds but not like the big block. 48-52 mph are just fine for the diesel and I lost interest in swapping the NP200 out.

The center output conversion is basically installing M37 parts on the NP200 since the M37 is what the NP200 was designed for. Vintage Power Wagons is where I got my kit from decades ago. I have no idea if they still have any.

The NP200 heat issue gets argued and debated on the M715 zone just about annually. The best I can figure. About 20%-30% can run all day with the engine at redline and have no problems. The rest can’t handle more than 2500 rpm drive shaft speed for more than about 45 minutes before they get extremely hot.

Putting a yoke on the parking brake output and driving the rear drive shaft from there completely eliminates the whine and fixes the heating issue in another 20% or so of the cases. I did that conversion on mine and love not having any whine.

However, mine still gets hot. So, I am in the other 50% that has heat issues. When I put the big block 396/NV4500 in mine I changed the NP200 to synthetic Mobile 1 gear oil. I was cruising along at 65 mph with the top off and after about 45 minutes I started smelling something burning. I pulled over and my digital thermometer said 285° on the transfer case case and climbing. I got back in and continued at 52 mph which is right at 2500 drive shaft rpm with my 11.00 XZL tires. 30 minutes later it was below 200°.

I started looking for a divorced NP205 I could afford. Finally finding one a year or so later. I got the brake bracket machined and using a spare stock cross member made mounts for it. My Chevy NP205 has different spline counts than the NP200. The last time I looked it was going to be around $500 for just yokes. Around that time my big block broke and I put a 6.2 diesel in the truck. It can pull the truck at fast speeds but not like the big block. 48-52 mph are just fine for the diesel and I lost interest in swapping the NP200 out.

The center output conversion is basically installing M37 parts on the NP200 since the M37 is what the NP200 was designed for. Vintage Power Wagons is where I got my kit from decades ago. I have no idea if they still have any.

I talked to Steve at vintage power wagons and they no longer have that available.. Did you have to lengthen your drive shaft.. He thought if the diff was not centered it would be a bad offset.. i have original rear in my truck.

 

[79 oshkosh 2323]

There is a yolk on the tranfer case where the E brake is.. it is a M37 yolk.. It dont look like the drive shaft will be long enough to reach it.. Is the angle that it is going to that E brake you’ll to much or will it be ok..