polaris outlaw 90 transmission issues
 

I have this Polaris outlaw 90 that I have been working on.
it currently sits with no swing arm, rear axle, or chain. I am able to start the thing and rev it. It runs pretty well after running through it.
My issue is the the transmission. I can shift between forward, neutral, and reverse, but i can hear it slap hard when I am going in gear (obviously there is no load on it since its not hooked up to a drive train)
Am I able to just take the bolts off the side of the transmission to see whats going on in there and possibly see if something is missing teeth, or is there more to inspecting it?
I checked the fluid and it seemed fine, I drained it so I can tear into it, but this is my first go at transmission work on one of these.
I cant find any pictures, how to, or anything to help guide me at this point which is scary because I can normally find something.
any help would be appreciated.

update
 

well I got impatient and tore into it.
To get into the transmission on it, drain the gear oil out from the bottom plug and there are 9 bolts (8mm) and it comes off similar to the other side where the flywheel and clutch are located.
You can take off the sprocket via (2) 10mm bolts then slide the sprocket and locking washer off. Then there is a snap ring holding the final diveshaft in place.
I figured out my problem pretty quick when chunks of metal started falling out.
I will need several parts including the main shaft, the final shaft, and the final gear, along with the housing.

anyone know where to get cheap parts other than the obvious ebay and genuinepolarisparts?
looks like about $450 in parts.
I hoped to find some parts on ebay or craigslist.. or someone parting one out, but didnt have any luck.
here are a couple pics of what im dealing with
https://cimg0.ibsrv.net/gimg/atvconn...500f6cb7d3.jpg
https://cimg1.ibsrv.net/gimg/atvconn...1bce70ccfe.jpg

The 2 stroke 90s had a bought in Chinese/Taiwanese "Minarelli clone" engine, but I don't know if the 4 stroke is bought in or made by Polaris. Doesn't look like either the GY6 or Honda cub clones favoured by the Chinese makers.