Lonnie:
Engine gasket set?
Was the manufacturer of your set kind enough to provide a list of the gaskets that the kit included so that you can figure it out by a process of elimination?
Without more information than rectangular and short/long, the only gaskets that come to my mind with those general shapes are those for the tappet covers and the valve (rocker) cover. But their material (cork -vs- rubber) are dependant upon the year of manufacture.
You might want to determine what you haven't reassembled and with those gasket surfaces in mind, compare the cork gaskets against a moss motors exploded drawing and descriptions.
Hindsight being what it is, this goes to show the value of written descriptions or photographs of old gaskets found in place during disassembly. Assuming, of course, that you are the one performing the disassembly.
Hope this helps.
Mike