Tried the different leak stops & no help. Going to try to replace the rear main seal with a friend. Any advice on other parts to change while we are under the vehicle & doing this job? Also, I have read where people recommend GM part # 12639250 which has the seal already installed. Is this correct? Is the summit racing Chevy performance 12639250 any better? Any and all suggestions are greatly appreciated. We have never tried something like this so we need all the help & experience we can get! Thank you!!