Hey David. All I have right now is this 240V little box heater from Northern tool. Works okay when it's about 25 degree's or more, otherwise it's too small.

NewAir Electric Garage Heater — 19,107 BTU, 240 Volts, Model# G56 | Electric Garage Industrial Heaters| Northern Tool + Equipment

I would have done a propane, but I don't have the venting necessary for it.