Found a few adds from Simplex and Manco with square tubing karts.

The engines was made on April 26 1968, just not sure about the go kart. Not really looking to sell, just info.
Thanks!

Anyone know where I can get info on a Simplex Fun Kart? Looked for hours trying but all I can find info for are the daul engine karts. Engine date code shows its a 68. Thanks for your time!