When I first received my 3600 the T-start was not working and did not have a block heater installed. Try not to "need" the tractor when it is too cold, but used ether a few times when it was cold to get it going. Put a block heater in it and a new Thermostart and haven"t needed ether since. Will start with only the Thermostart down to about 15degF, maybe colder but I plug it in if its going to be colder than that.
For the few dollars involved and pretty simple installation (unless you have a loader frame in the way) go ahead and install it. Doubt you will regret it.