Mystery heater: Seen in a Series, where does this heater-box usually live?

[Landrover17H]

Only a day or two ago I fired a query at you blokes about identification of an air-filter box seen in a Series. You all seemed to swat it back at me with a clear answer in hours, so if you don't mind, can I throw another at you?

Seen here is a Series with a 2.5 17H Petrol sitting in it, but it's the heater-box that catches the eye. I'm afraid, found listed in eBay, these are the only pix I have. Series heaters are a legend for not being up to much. Top right of last piccy shows it best.... what's this we're looking at, is it a Defender heater-box from later? Why the moulded-arm shown Bottom-right of first piccy?

Edited September 22, 2020 by Landrover17H

[Snagger]

I don’t know what the matrix and plastic front end/duct came from,  but the rest of it looks fabricated to me.
 

SIII heaters are ok if they’re in good condition, but once rust holes appear in the blower housing, the corrugated hose splits, the matrix bungs up with congealed damp and dust, the fascia trunking is perforated by screws for additions and the foot well vent flap foam seals crumble away, it gets very weak.  Add a seized coolant flow valve and a few decades worth of scale and rust inside the pipes and matrix, and it’s no wonder they don’t work well.  Like the brakes and steering, their reputation is unfair, caused by neglect rather than poor design.  A full strip and rebuild sorts it out and yields good results, but the heat leaks straight out again if the doors and bulkhead vents don’t seal properly, and given the poor fit of almost all pattern part door tops, that’s like peeing into wind.

[Landrover17H]

I could swear I placed this in the Defender section. Clearly I didn't or our Idi Admin has moved it? Looks wholly a lump of plastic to me, but now you mention it I see what looks like a row of pop-rivets? 

I've a Defender version in mine. Works better but, as you said - with so many other holes about, it'll never be great.

Edited September 24, 2020 by Landrover17H

[western]

I moved it as it is not a Defender specific post. 

[Snagger]

17 hours ago, Landrover17H said:

I could swear I placed this in the Defender section. Clearly I didn't or our Idi Admin has moved it? Looks wholly a lump of plastic to me, but now you mention it I see what looks like a row of pop-rivets? 

I've a Defender version in mine. Works better but, as you said - with so many other holes about, it'll never be great.

The matrix is about the same size as the Defender unit, as is the blower.  I don’t know if the Defender motor is more powerful - it’s quite possible, but the condition of the system in either vehicle has so much effect that it’s hard to know if there is really much difference in the capacity of the parts when new.
 

 I have a Defender heater, too, and fitted Defender doors and seals to stop the drafts.  Between that and a rebuild of the dash, and other components  of the system,  I find the standard old spec Defender heater ample in UK winters in a 109/110 hard top.  The biggest problem is the time to warm up with the 200Tdi, which seems much longer than my 300Tdi, even though the 300 has its driven fan and the 200 and electric fan which won’t be cooling the outside of the block.