Differential cover gasket
 

I am trying to change the differential gear oil in my 1968 Olds 98 (455 engine). I purchased a FelPro gasket # RDS 55029. However, this gasket is to small (diameter). I called the auto parts store and they are ordering another FelPro gasket # RDS 55009. Does anyone know if this one will fit? A quick measurement of the cover bolts appears to be around 10" from a top bolt to the bottom bolt (directly below the top bolt). Any information is appreciated. Please email me at psh1964@gmail.com

Thanks,
Phil