[kipps]

Originally Posted by SunSoaked

I'm thinking there is several ways to make the swap depending on what parts are used.

I'm getting ready to begin my swap in the next few weeks. I'm swapping the 400/208 for the 4500/AA spacer/205 t-case.

My biggest issue is determining if I need to run a two piece rear shaft due to the overall longer length because the 4500 is shorter and the 205 is way shorter due to the fixed yoke.

What is/was your setup? I'm assuming your 241 has a slip yoke?

Sorry, I'm just now seeing this. Yes, my former 208 and my new 241 both have slip yokes. My driveshaft is 3.5" diameter, and 53" in length between the u-joints. This does not count the length of the slip yoke. I neglected to measure that.

The reason a lot of these parts have the same exact dimensions, is because GM was swapping them in the middle of a model run. The sm465 got a different bellhousing(passenger side external slave) and an aluminum shift cover with a more rearward shift position, when it was installed in the gmt400 trucks. The rest of the transmission remained exactly the same as the one used in the 87-91 R/V trucks. When the sm465 was swapped out in the middle of the model run for the nv3500/nv4500, those two transmissions were sized to fit exactly in the vacated space. In the same way, the np241 took the place of the np208 during the gmt400 and R/V model runs. Again, it only made sense for GM to spec the np241 as an exact drop-in replacement. In contrast to this, the switch from Gen-1 small blocks to Gen-3's occurred at the beginning of a new model run. Because of this, these engines don't swap as easily. GM obviously wanted to use their former transmissions with the new engines, so the bellhousing patterns remained the same. But since they were changing the chassis at the same time as the engine, there was no need to keep the engine mounts in the same place. That got a little long winded, but it's illustrating a principle. Look at an issue from GM's point of view. If it was in their best interest to make several parts interchangeable, they probably did.