DeansZG and Leo are right. That part definitely belongs inside your engine.
I just had my GPZ's oil pan off a month ago. Its almost identical to the C10's.
The hole Leo refers to is angled up towards the rear of the bike, into the crankcase, just above the oil pan gasket. The angle will be similar to the angle of the tube in question as shown in the fiche. The GPZ oil pan had the same type of tube, just with more of an 'S' shape, that fit in the same type of opening in the same area.
Dean's idea about maximizing your access and visibility is key here.
There are a bunch of things that need to remain lined up perfectly in place to get the pan back on.
I was able put my pan back on the bike while on the centerstand with me laying on the ground. It was awkward to get the pan up there and secured, while making sure that the gasket and everything else was aligned OK.
I got it on, but not very smoothly, causing concern that the fat dowel on the oil pump assembly or the thick beveled O-ring next to it could have fallen or been moved out of place.
I ended up pulling the motor, and put it upside down on a bench. Then I took the pan off again to make sure everything was OK, which it was. At least now I had peace of mind that all is well there. Would have always wondered about it otherwise.
It was much more manageable to install the oil pan this way, as I could see everything in its place.
The GPZ engine may be easier to pull than a C10's since it doesn't have shaft drive, although I've never pulled a C10 engine. Not saying you HAVE to pull the engine to do this, but if you have a bike lift so you can see and work better, along with a helper to assist, all the better.
I found it easiest to have most of the parts in place up in the crankcase, with the exception of the plastic sump screen assembly before putting the pan back on. Most of those parts hold in place fairly well, but it doesn't take much to knock them loose. Just be patient and exact.
While you're in there, best to replace all those O-rings. It will help keep the oil pipes in place better during re-install.
Here's the parts that need to line up between the oil pan and crankcase.
p/n 32033A
32033
92190 (your part in question)
as shown here:
Crankcase fiche p/n 671 The internal O-ring (same size as oil filter's)
as shown here:
Breather Cover/Oil Pan fichep/n 49065 and O-ring
92055
92043B and O-ring
As shown here:
Oil Pump fiche