I was under my truck alot today and I was noticing that the 231HD case that is in my truck (01 with a 318) uses the common 6 bolt round bolt pattern. I was considering mounting a 203/205 behind in the NV3500 for quite some time but I have not been able to find the 6 bolt round pattern adaptor or 203 with this pattern. Does this exist?

I too have been looking into this. Got a 203/205 setup waiting in the wings for my 231 to die. I dont think there is a Nv35xx (mine is a 3550) to 203 adapter. But with a little bit of work you can directly mate a Dodge 203 to the NV35xx. I dont think there is a round bolt pattern dodge 203 but from what I understan its relatively easy to drill and tap the face of the 203 with the racetrack pattern for the round pattern. Then you need to do a little bit of machining on the bearing retainer to fit in the recess on the back of the NV35xx. This thread (http://www.pirate4x4.com/forum/showthread.php?t=181232) details the work needed to fit a 4500. I figure it will work for the 3500.

Edit: Looks like the pics are gone. :(

I was looking on the www.northwestfab.com site and found that they have a 23 spline Dodge input shaft for the 203.

http://www.northwestfab.com/images/DSC00065.JPG

23 spline Dodge: $149.00 USD
/w New input bearing and Seal: $174.00 USD


They also have these adaptors available with the 6 bolt round mounting surface. I am just not sure if it is concentric or not.

http://www.northwestfab.com/images/chevround.JPG

http://www.northwestfab.com/images/DSC00408.JPG

I also have 2 203 range boxes and 2 Ford 205's.