Blown Head Gasket? on 1995 Ford Taurus

Just a month ago had a new/used engine put in this vehicle. Already it has white smoke from exhaust which I assume is a blown head gasket. No overheating and engine light only blinked occasionally. Is this mechanic error for not using spec to bolt? Or...driver error? Need opinions please.

Asked by for the 1995 Ford Taurus
The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. I think the napa part number 700-1006. . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix.
I have tan sludge coming from raditor and reservior. I do not know what equipment I need to get to repair what I was informed was "Blown Head Gasket" What to do! Also can you send me a picture of where the oil plug is located on my 1998 GMC Jimmy 4.3 V6? Also, what can I use to loosen oil plug and radiator wing nut? Desperate Woman in Stone Mountain!!!!!!!!!!!!!!!!!!!!!!!!!