Chevrolet: engine work, loose bolts, monte ss

Question
i know this is a bit out of your field but its pretty basic and GM, i have an 87 monte SS and she's got a bit of an oil leak. its my first "project" i got her cheap n all, but anyway ..it appears it leaks while driving, or shortly after stopping,  i just looks under it and its been sitting for an hour or so, and nothing dripping, but it has a puddle, (which has since reduced in size since i replaced the valve covers, and gaskets)....and gotten it away from the headpipe =) ....but now the small puddle remaining gathers around at best guess the rear main seal area, or if the previous owner did as bad  of a job  on the valve cover gaskets.....it could be the tail end of the oil pan.....i figured if it were the timing cover or front seal, the puddle would be up there, it gathers in a best i can decribe..."horizontal
band"  going drivers side to passengers, and seems to be about the meeting point of engine/tranny, so im asking, how could i tell if its the back or the pan or the rear main? and if the main seal had failed wouldnt it not run or lose all the oil? the book tells me how to replace em, not how to tell which one failed LOL well sorry for the long windedness, but i know how hard it is to diagnose something like this without seeing it, but id rather ask someone who knows better than troubleshoot with my wallet LOL

thanks in advance,
john

Answer
John;
HI with the oil it can travel it might be comming from the valve covers or from up top and running down, I would re-tighten the valve covers and than clean the enging with a can of gunk than after its clean you will se a lot better where it mightbe comming from, it could just be loose bolts , check them out.