Dale there is a link at the top of the home page for parts on these old bolts. However for what you need, you can get them at most any auto parts store.
Also if you have a 235 in a 42 model truck the engine has probably been replaced. The 41 I am working on has a 235 from a 56 model and I am installing back the origional 216.

I didn't do it, no one saw me do it, you can't prove anything! "Bart Simpson"