The following discussion asumes that you have a four cylinder 4000 with five speed transmission. Ignore otherwise.
The plate held in place by 5 bolts is an access cover for the relief valve and also a good place to clean accumulated sediment.
If you remove it be advised that there is also an alignment dowell to contend with.
Bite the bullet and buy a proper gasket from CNH for it. DO NOT use ANY goop.