Hello, I have a 46 Chevy Truck with a 235 engine from a 58 or 59 Chevy, numbers 3836846 GM 14 (see picture link). I have a 6 volt system and I am trying to install a new ground strap from the frame to the engine block, but I can't find the size of screw that fits in the block (see picture link). I have tried 3/8 and 5/16 and neither fit right. Does anyone know the correct bolt size and where I can but them?

My 235 Engine Numbers

Engine Block Screw Holes I want to Use For Ground


1946 Chevy Truck Export Blue with Black Trim