Take one of the bolts out of the rear cover and see if it will thread into the front "pig" bolt holes. If it's the same thread then you will need to determine the correct length needed. From there it's as simple as going to your local hardware store or good auto parts where you can find the fasteners. Grade 5 should be sufficient.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy