I knew a while back that Cox produced several types of cylinders for the reed valve .049 over the years and 2 or three different types of crankshafts (the beefier ones for the Cox cars) and even 2 or 3 case variations (the early conical nose and the later straight nose) BUT WHAT ABOUT PISTONS? I thought all Cox .049 pistons were created equal. Imagine my surprise when I disassembled a .049 reedie Baja Buggy engine (the one with the worm gear and pull start) only to find that the piston first had a beefier connecting rod which was quite thicker at the crankshaft end and tapered down as you go up toward the piston (all my other Cox connecting rods are of uniform thickness) and while it has the usual ball and socket connection it's different from the usual piston which has the socket "shrunk" around the ball of the connecting rod in that the socket is secured in the underside of the piston with a tiny circlip and looks like it's removable!