S4 lens tube identification

I am cleaning my mostly old Source 4 lenses.  One lens tube has a configuration I've never seen before.  See photo.

The front lens slot says 19, the next one 26, next is 36 (in most lens tubes these are right next to each other, here they are over an inch apart), I think the next slot is 50 and the last slot is not labeled but I believe it is for the second 36 degree lens.  I have never seen this configuration of lens positions before. I cannot find anything that looks like this in the lens configuration manuals.

There are two lenses in this tube.  One in the far right slot (that I think is for the second lens of a 36 degree fixture - and the lens looks like the rear 36 degree lens).  The other lens looks like a 36 degree lens but was in the 26 degree slot.  I think the lens is too large to fit in the slot labeled for the 36 degree lens.

Is this a 26 or 36 degree lens assembly?

Any help is appreciated.

Larry Pint