Come to think of it in about 2nd or 3rd grade I had one, only it wasn't from any of the X-Marts as I don't think they were around then...well maybe the "K" one was. Anyway, mine was from Sears, right out of the "wishbook". It was probably the 1st FS bike available. It was kinda' like a Schwinn Stingray w/ the banana seat which was supported on either side w/ two "coil shocks". It had some sort of springer front-end like a '47 HD Knucklehead. It also had a 3-speed "grip-shift". Man now that I think about it Sears really was a forward thinking company!!! A big honkin' multi-speed FS bike in the late '70's!!!
Only problem was that it probably weighed as much as the heavier DH bikes and it was mighty hard for some 8-10 yr old legs to pedal all over town! Those were the days...an 8 yr old could ride all over town w/out being abducted or molested!