Replacing a Rockwell T221 with an NP205

[Donald Clemens]

Well I managed to install the NP205 where the T221 transfer case (TC) used to reside in my 1968 GMC K2500. I moved the supporting crossmember back 2 1/2" which required drilling new holes in the frame. The side support with the rubber bushings bolted right up to the NP205 and matched one of the holes in the horizontal portion of the frame. The piece of this side support that bolts to the verticle portion required 2 new holes. After bolting up everything the NP205 was rubbing against the bottom of the floor pan and it appeared the output yoke was also high enough that the driveshaft was not going to clear the frame crossmember that supports the center driveshaft bearing. I tried lowering the TC crossemember 1" but found that my HEI distributor was now hitting the firewall. I have since gone to a 1/2" lowering which seems to be ok. Now when I run a string line between the TC yoke and the rear differential yoke, after removing the center driveshaft support bracket from its supporting crossmember with my torch, I have about a 1/2" clearance between the string line and the remaining crossmember. It is probably slightly more than this since the driveshaft tube is smaller than the bolt holes in the yokes. Has anyone had to cut this crossmember? ( The one that supported the driveshaft center bearing.) Secondly, does anyone know of a one piece driveshaft that will now work between the NP205 and my stock rearend? One guy mentioned he thought a 69 to 72 1 ton might work?

[1969K10]

For what it's worth, my local drive line shop would not create a 1-piece rear drive shaft for my conversion. He said it was too long to be safe. I ended up moving my carrierer bearing support & shortening the rear drive shaft section.

[Donald Clemens]

1969K10
I have ordered a new driveshaft from Tom Wood's Custom Drive Shafts out of Ogden, Utah. They had no problem with the length. Mine needs to be 58 7/8" with a 4 degree slope. It has Spicer 1350 u-joints at each end and a 3" slip joint. Tom's only advice was to increase the diameter from the original 3" to 3 1/2" which I did. He has an excellent web site that provides you with a "Complete Measuring Guide". He is well known and respected among 4WD gear heads that do a lot of off roading with highly modified (lifted) vehicles.

1968K2500

[Yukon Jack]

Will be interested in seeing your new driveshaft. Is he building it in aluminum? What is the ballpark price?

Is your truck a short or long bed?

Alot of the newer trucks have long rear driveshafts and like he's doing for you, it looks like a larger diameter is used to give more strength to avoid any deflection.

[Donald Clemens]

I received the new drive shaft from Tom Wood on Thurs. 7/17. I placed the order on Monday, 7/14. It is made of steel and had a shipping weight of 37 pounds (UPS). The cost was a total of $304.00 including shipping. It went right in after I modified (cutting torch) the cross member that use to support the old center carrier bearing. After cutting, I reinforced this cross member with a C channel for stiffness. The skid plate attaches to the frame at the same point and should provide some stiffness also. I have only test driven the truck a couple of miles, but all seems to be OK. I'll provide updates as I get some additional miles on. The only other item that required some modification was the emergency brake cable. It now runs under the drive shaft where it used to be above. It actualy crosses under the rear output shaft housing of the NP205. By the way the slope on the new drive shaft is 4 degrees. Check out Tom Wood's site at www.4xshaft.com. Also, my truck is a long bed fleetside, with stock suspension.

[Yukon Jack]

That's quick!

[Yukon Jack]

Any chance you could shot a few pics of your undercarriage showing the transfer case, rear driveshaft and what you had to do to modify the crossmember for the rear driveshaft clearance and an interior pic showing placement of your NP205's shifter?

My swap plans have changed and I'm probably just moving my t/c back like you did rather than moving it foward.