Where have[the one's with cab's and heater's] tied into the motor on there BX tractors. On my D 902 engine on my BX 2370-1 there is a 3/8" NPT plug just under the thermostat that I can remove and put a fitting in to feed the heater. Now the return from the heater would go where ?? All I can think of is that I can get a tee and install it into the lower rad hose [as close to the water pump as possible] it's pretty tight with the Alternator and belt running so close to the hose. Of course where there's lots of room is where the hose has bends etc; Now one thing is do I remove one of the small freeze/frost plugs on the right side of the engine block.Those plugs look to be 3/4" OD. Now what would it be like if I was to make a fitting ?? fit into that frost plug hole that would install the same way as what the block heaters do. It would have to be a snug tap in fit that would be held in with Red thread locker. Once that part is installed I could thread in a 3/8" NPT fitting into the end and connect the return from the heater to that. What do you guys think or do you have any ideas other then returning and feeding from the bypass hose ?? Thanks for any ideas.