Mystery lower unit

[Merc 2.5]

Ive had this lower hanging round for yrs and today I decided to pull apart and inspect it , I'm not around to get #s but I will tonight, by parts diagram search of all different models, it seems to be xr4 because shift cam seems to be specific to the xr4 or maybe early 79-82 2.0l. I got pic of cam and ****ty pic of lower , let me know if anyone recognizes it because it seems to be a odd ball , the shift shaft dosent have to be removed to pull carrier and prop shaft unlike normal 2.4 ,2.5 edit i put a carrier in it from a known 2.4 200 so I'm back tracking on xr4 case cause wouldn't it be smaller?
stuff

[Merc 2.5]

So # comes up old 2.0 175 2:1 ratio but the parts diagram dosent look like what's in the lower unit , im stumped and don't wanna order wrong parts if i can help it. The cam and follower (pin in end prop shaft) is this 44 45 (pin) but # on case is pulling this up 50 51 52. Not whats in mine

[skialot2]

What does the top of the drive shaft look like? Does it have a preload pin? Is there a nut holding the driveshaft bearing race down in the case?

[Merc 2.5]

Ya it's preload , I got everything figured out , all parts was same besides ratcheting and preload and had 2 different configurations of the shift cam for whatever reason. I got seal kit ordered. I'm just resealing it so I'll have a spare unit ready to go if need be , internals looked new. Hardly any wear at all. I appreciate ya tryin help but I got it figured out with help of marine engine

[25two.stroke]

Yeah. Old old old. Pre "EZ-Shift"

[Merc 2.5]

Yeah. Old old old. Pre "EZ-Shift"

I think it came off old school 175 but showed they made em up into late 80s but seem they were hit and miss , according to marine engine anyway, it's just one I'm keeping to the side for a spare since it's in good shape