inspection hole in bell housing?

[450cgreenhorn]

I've got a 78 JD 450c, had the floor plates out the other day and noticed a 2 inch inspection hole on upper left side in what i'm guessing is the bell housing. previous owner had duct tape covering it but wasn't doing a very good job.
what is this hole for? Does it need to be covered/sealed at all times? anything I should be worried about if a little dirt and leaves fell in the hole? should there be any oil in there, if so how much? and what kind?
Thanks

[LeonardL]

The hole you refer to is an access hole for adjustments to the main drive clutch as well as the HLR mechanism. Deere had a rubber plug to fit in this hole to keep debris out and yes you should keep it covered. However, Deeres rubber plug can be a real bearcat to install and an even worse perhaps a pissed off bearcat to remove! You can either get one of these plugs from Deere... which I still recommend even after the above description or you can get a simple plastic plug or cap that will fit snugly in the hole. I know of a couple of guys who have a plastic hydraulic hose cap or plug that fits perfectly in the hole and is a lot easier to remove if need be. These plugs they use have the name ( Caplug ) on them. Usually found at any good hydraulic equipment source. Duck tape is not a good enough cover in spite of its reputation. And no there shouldn't be any oil inside this housing.

[450cgreenhorn]

thanks for the info and ideas