Where is my Transmission Cover Assembly?

[quadzilla200]

Hey All,
I have a Blade 150cc buggy (Vitacci, Apollo, Fangpower). Goes by a bunch of names. My kids trashed the transmission fairly quickly so I've got my new variator and clutch, but I'm really thinking there are some issues with the bearings inside the gear case. What I'm completely stumped on is my unit does not have a https://www.amazon.com/Chicago-Scoot.../dp/B06XDH84T3 . It is a solid block in there. It is a short case 743mm. I have no bolts I can take off to get to the gears and bearings. I'm stumped. Surely you wouldn't have to take out an entire engine to fix an issue like that? All the YouTube videos I've found has that part.
Also, does anyone have any idea what that large bolt was underneath the transmission. I originally took it out on accident, thinking it was the transmission oil drain, but it was this huge hollow bolt with a ball bearing and spring pushed down which popped out when I undid it. I put it back up there, but I'm not sure it's as it was. Any help would be greatly appreciated. I feel like I bought a kart built by Gremlins.