spacers are 1/2 mild steel with hole drilled in center for bolt. If you want a pic pm me a e-mail and I will send you a pic of the spacers. 383 is not that hard to get in an a-body, 440 is much more challenging. Overdrive I hope is a cast iron case ? version. If you plan on slicks be warned small bolt pattern 8 3/4 axles and slicks end up sounding like a little kids vacuum popper lol. Make sure you have frame connectors and a drive shaft loop.