Hi I am looking to put a small refrigerated unit on the back of my 4 door diesel D-Max pick up . Does anybody know of manufactures of such in Thailand ?

How small?

Custom fitted on the tray area either buy removing well body and fitting or on top of well body approx 1.5x1.5x1.8 m

I don't remember the name, but there is a place that has a big sign on the left-hand side of the Rama 9 motorway betteen Srinakarin and the new airport.

custom made kind of fridge, right?

Buy a small unit, rip out the technical things and put it in your custom made box....pretty easy to do a couple of years ago.

(Unless the added some complicate electronic)

I think he just wants an ice or ice-cream type truck body. Pretty much an "off the shef" kind of thing.