It is a RWD normally, with 4WD selectable by one lever, and 4WD HI/LO selectable from the other lever.
The helical portion of the gear is used (I believe) during 4WD HI (1:1 transfer case ratio) and the straight-toothed portion (I believe) is engaged during 4WD LO (2:1 transfer case ratio).
I have read on the internet that this Dana 20 transfer case can be easily made to have a 4th operating mode (FWD) simply by removing some pin or block (I can't remember exactly and not really curious) from the transfer case.
But in any case, there is most definitely at least one (probably two) approved operating mode where that straight toothed portion is not engaged with anything and all the side load from the gearing is handled by the bearings in the transmission and intermediate housing.

OK, and I am glad that you have a good handle on that part because it is beyond my realm of competence.

 

This intermediate housing contains an additional bearing near the end of the shaft, right before the transfer case gear. The fact that the transfer case does not have any bearing to support the very end of the shaft, indicates to me that the bearing in the intermediate housing is sufficient to handle normal side-loads. The fact that this gear is a helical gear, indicates to me that it is also designed with resistance to axial loading. I suspect it will be fine coupled to a PTO shaft, but I'm open to opposing theories.

You should be OK with the extension housing bearing. The T-90 tranny looks like one from a Jeep, what I'm most familiar with. It's output when used with the Jeep transfer case was supported by the rear wheel drive shaft bearing.

 

The shaft from the PTO to the trans has a universal joint at each end. They ALWAYS do. It is a long way from a cantilever.

So you say. I totally disagree though from experience. But that said I was going by what you posted/said earlier, about just having "a universal joint". One non-CV universal joint by itself is a recipe for disaster at any RPM like is being discussed here.

 

So you say. I totally disagree though from experience. But that said I was going by what you posted/said earlier, about just having "a universal joint". One non-CV universal joint by itself is a recipe for disaster at any RPM like is being discussed here.

I never mentioned what would be on the other end of the drive shaft that had a universal on the one end. I leave that up to the TS, who seems to be quite aware of how mechanical stuff should be done. What I do not say I leave unsaid.

 

Thanks for bringing it up. I'm aware of how universal joints work and the cycloidal (is that a word?) error they cause when used independently, and that one should always have a complementary universal joint on the other end of the shaft at an equal angle to (almost) cancel the error. If I needed to make an angle (just one) I would use a CV axle, and I have a couple of those laying around waiting for a new purpose in life. Though I don't think they'll be needed for this project.

 

You should be OK with the extension housing bearing. The T-90 tranny looks like one from a Jeep, what I'm most familiar with. It's output when used with the Jeep transfer case was supported by the rear wheel drive shaft bearing.

Yes the T90 was also used in Jeeps of the period. I was not aware of the difference in output shafts though. I guess it's fortunate that I stumbled upon a Scout T90 before a Jeep one; makes life easier.

 

I would use a CV axle, and I have a couple of those laying around waiting for a new purpose in life.

There is also the double U joint that the later model Fords used in their driveshaft if you want to shorten things up. They used the close coupled/double U joint to get around having to use a carrier bearing and split drive shaft, so that made 4 U joints in the drive shaft though.