A truckmount is a collection of parts, you need to think how much it will cost if each off these parts fail
The engine is new so that's ok, the pump will cost £350 to replace with a new one, (although it rare you need a full replacement) the blowers are usually bullet-proof although it is old they last for ever...... but if it needed replacing its £1200.
The exhaust heat exchanger is the big item and on an old machine like that a replacement will not be available, if it's stainless steel and has not been repaired then it should be ok.
Everything else is either replaceable or can be bypassed.
Did I read They are giving it a 3 month warrentee? If it's a lemon it will show its self in 3 months of hard work