Dunno which flavour 240D you have or if it'd make a difference so i've guessed
Mercedes-benz | iAUTO.lt_123.123 as an example. Pick a rad part number (i guessed without aircon) and stick it in the search engine of your choice and you should get some results that lead to hits like
Spare Part 1235011201 offering various different brands. Same part number but followed with nissens should get you some hits for the equivilant Nissens rad which is probably similar quality to an aftermarket Behr-Hella but typically better value, made in Denmark and not cheapnese tat. If i picked the wrong flavour of 240D then just scroll down the list until you find the right one
Mercedes-benz | iAUTO.lt
Dunno about "genuine" MB Behr rads but AIUI (maybe wrongly?) Behr stuff these days ain't the same as it used to be and probably made in South Africa IIRC? The Nissens rad i stuck in my s124 a few years back fitted perfectly, the core wasn't cosmetically quite as nicely finished as a Behr but on the flip side the plastic tanks had thicker wall hose stubs while the old behr rad i was replacing were much thinner with a copper ring bonded into them which makes for a nice stress riser compared to the Nissens way
For the waterpump i used
Sparepart groups for Mercedes 123.123 (240D) which is bit easier to navigate but doesn't go into as much detail. On the plus side it includes (usually only decent) manufacturer part # as well MB for example
110 200 1720 O: WATER PUMP for Mercedes 123.123 (240D)
Stick the producer no from that into the internet and the first hit is
Water Pump (SKF , VKPC 88807): MERCEDES-BENZ Parts - Bestpartstore.co.uk. German Company with a UK phone number and no pratting about begging for [cough] "discount" [cough] codes to get the "real" retail price