Reference my 99 D1, 4.0L AUTO, 177K:

I checked rave and have seen conflicting, albeit minimal guidance on this question. Also searched here but probably using poor terms?

Here goes, there are two hoses, identical, that serve as the in and out flows of coolant to the heater from the coolant system. The two that end up at the firewall, just left of center. Now I always heard our trucks do not have a valve in the heater and that coolant just flows through on something on an open loop. RAVE alludes to there being a valve.
If there is no valve, does it matter which hose feeds which?

I'm pretty sure I reversed mine after some repairs and I've looked at every pic and video I could find online and I've seen the hoses go both ways. Some feed from the manifold and others seem to be feeding from the pipe that runs up the front left of the block.

I need a drink, this trucks been kicking my *** all week with little things. LRs are without a doubt the quirkiest, most patience trying vehicles to both work on AND find information for.

 

In the pic #1 heater hose(LEFT) is routed to the manifold through small hose PEH101530(it different diameter ends). The #2 hose(RIGHT) is fed from the lower radiator hose.

This is what the all of the hoses look like and there is a video that will help explain locations> Coolant Hose & Thermostat Kit: Advanced Evaporative Loss System (9370SKF Same Fit As Part # 9370SKF ) - Land Rover cooling/heating from Atlantic British

Go NUTZ!