Are you talking about item #106 "Backing Plate"? If so, it's not required, but it is used to attach the torque converter cover. If you plan on putting a cover over the torque converter, I'd recommend some sort of back plate.
Without more pictures, it's hard to figure out the model. My best guess is a Manco 485. Here's a link to the manuals for the 485 series karts. Take a peek and see if you can match yours up.
That will give you a source for all the Manco part numbers. If you go with stock-type components, you'll...
If it is indeed a Model 435B Manco Eliminator (link to manual here), it did have a jackshaft.
It shows a 9 tooth and a 35 tooth sprocket on the jackshaft as well. Axle sprocket is 27 tooth. Clutch is 10 tooth. Tires are 145/70 x 6" which is about a 14" diameter.
Oh, the cooling fan! That is factory installed. There is a vent on the TC cover too. I guess they ran hot. It is warped though and it looks like the replacement is metal so it should last longer.
Yeah, it's gonna need a bit more than cleaning! But I think it'll clean up okay - I've got to watch some videos about cleaning up rusty torque converters.
Hey folks! I picked up a Manco XTK-710E off a guy I work with. I don't know how much I paid for it though - he just dropped it off and said we'll figure it out later!
Anyway, it's been sitting a few years so it needs a bit of work. It also ran into a tree at full throttle (with no-one in it) :(...
The coil-overs are original... but there is very little clearance between the A-arms and the lower frame rail, so there is no way it sat much higher.
And yeah, I'm not too impressed with the structure of those spindle brackets.
Okay folks, as mentioned in my other thread, I got a Manco XTK-710E go kart.
Among the few issues it has is a problem with the front A-arms. Both front wheels have a high amount of camber so it looks like this from the front: /---\
It doesn't look like they are adjustable. I might be able to...
Well, it's not a 13HP as the guy thought, it's an 11HP Tecumseh. It's banged up in the front a little bit - just the cage though. I'll have to go through it and check it all over.