Hey guys, I have a 347 that I am having trouble getting the oil pan sealed up on. I purchased the long block around 2005 from Coast Performance and thought it was a later model block used for the build, but the last 2 gaskets I have purchased don't fit very well on the rear main seal area of the block and I am getting a leak. To be certain I get the right gasket this time, I pulled the date code of the block (the number that sits just above the starter) which reads "4C23" which I believe translates to 1964 block. Would appreciate if someone could fact check me. The engine definitely has a 1 piece rear main seal and runs hydraulic roller lifters and uses the spider hold down in the lifter valley. This plus I thought I recalled reading that Coast Performance used later model (86-93) blocks for their stroker engines. I have tried the Fel-Pro 1 piece gasket, the Ford 1 piece gasket and they both leaked. I recently ordered a Fel-Pro 1809 gasket and the front rubber end seal fits good, but the back rubber end seal seam a little big. I don't want to put it back together until I know for sure I have the right gasket this time. Appreciate the assist!