try to find out were the oil leak is come n from on 1991 Chevrolet S10 Blazer

i have an oil leak it looks like the oil pan gasket but the oil is driping from a silver round pice on the right side of the pan what is that pice it has two tubes going out of it

That round piece is the adaptor for the oil cooler lines and the tubes going out if it are the oil cooler lines which go to the radiator. The adaptor plate or the lines could be leaking.
can you tell me how to change the seal on the oil filter supply and return at the engine side? Looks like I cannot get to the bolt to remove plate at the engine and the transfer case is to close.
2 more answers
perhaps your engine oil cooler tubing o-ring seals; engine oil cooler seal kit
oil cooler attachment(normally the oil filter would attach here but for the transfercase would be in the way