What Galen is trying to say is that your Mahindra has a 3/4" NPT plug that you remove... to install a 3/4" heater in it's place. On my 5035, in the lower radiator hose, Mahindra has provided a big cast iron inline holder for installing the screw in heater. Your 4530 may have a similar setup, or you will find that 3/4" NPT plug somewhere else. If you don't want to buy a screw in heater from the Mahindra dealer, you can find them on Ebay or Amazon... Just make sure you do not buy one that is too deep for the hole it has to be screwed into. You can still go freeze plug if you want, just don't have to... I don't think my 5035 even has 'freeze plugs'... you know, the big holes the engine manufactures put in the side of the block so they can hold the sand form in place, then clean out the sand from the casting process.... press in some steel plugs.... and call them freeze plugs.