I recently bought oem valve covers chrome for my 69 390 motor. They don't fit over adjustable rockers. They are the ones with not "powered by ford" lettering and I wonder if they are for an older 390. Aftermarket valve covers are a dime a dozen but I am not sure to look for or buy in oem. Can anybody help? Can't just keep on buying different ones and bringing them home to try them on. I believe rockers are oem.