hI have a 2001 chevy express 1500 conversion van with the 5.7L V8. I had replaced the timing chain at appr. 190k and the timing chain cover and gasket (they come together as a kit) along with the oil pan cover gasket. What I did notice when I took the old oil pan gasket was that the front part of the oil pan gasket that mates with the timing cover was cut off (the curved part of the oil pan gasket). On the 2001 chevy express van the front of the oil pan is actually curved rather than flat. Anyway for some reason someone before me had cut that curved part off and replaced with sealant apparently holding the timing cover and the oil pan together (over time I believe that a leak developed around the timing chain cover area as seen by heavy oil residue). The oil pan gasket comes as one large piece with the curved area. What I did notice after installing the oil pan with its new felpro one piece gasket and then trying to install the new timing cover with it's built in gasket, I noticed that they did not fit and would not mate together as if they were very misaligned by a large I would say 1/2" gap at least. The timing cover itself was nowhere near being able to sit properly on to the oil pan gasket and there was quiet a large gap to be filled with the rtv sealer. I have seen videos of people installing a timing cover gasket and then installing the oil pan gasket over it without issue (on an engine mount upside down, out of the vehicle, super easy). For whatever reason I was unable to mount the timing cover on to the oil pan gasket properly as I have had oil leaks while the van is running and no leaks when it's off. Reason I replaced the timing chain was due to the heavy misfiring issue i was experiencing. After the timing chain and components replacements the misfiring was gone. Idles great. Then I noticed the oil leaks. Wondering if putting the timing cover on first and then the oil pan gasket last is the way to go or if it even matters. When I put the oil pan first and then the timing cover next, it seemed like the gap was way off, unbelievably off. Any tips and tricks would be appreciated, maybe theres something I missed...let me know, thanks.