I have an old suburban that someone stuck a big block in but I cannot seem to identify it. The last 3 numerals stamped on the pad are 7FD. I cannot see the casting numbers on the back of the block as it is too tight to the fire wall. I tried using an inspection camera with no luck. It is chevy orange but could have been painted years ago. I guess I can cut a hole in the firewall if need be. It runs like a top. Also there are no serial numbers stamped on the pad so I suspect it is a replacement or a marine block.