The overall length of the Doubler™ is now 21.5" for all versions. This is measured from the front face of the 203 to the rear yoke centerline on the 205. This is the same length as the original 203, and only 6" longer than original GM 205 applications. It's 9" longer than a 205 for the Ford guys. The new compact length allows the Gen2 Doubler™ to fit in many more applications while still leaving adequate rear driveshaft length. Keep in mind these measurements are not absolute, they can vary as much as 1/2" either way depending on the case length variations and yoke length. This does not include the adapter between the transmission and NP203.
This is off of
www.offroaddesign.com. They don't actually say why they use the 203/205 setup instead of 205/205 the info seems clear, why? Why would you want to use 205/205? First off the weight of one 205 is a back breaker, but two! Secondly the length, as they say with their adapter the 203/205 combo is the same overall length as the 203, what could be better than that? Lastly the parts and the info are already there, the work has been done, not to mention that you would still end up with a higher overall ratio with 205/205. I personally don't see any advantages to the 205/205 combo, if i am missing something feel free to point it out