coolant system - metal pipes (and an intro)

[BlackRedGold]

hello all, i have been lurking around for awhile now and decided to interact. a couple months back i bought a single-owner floridian 1983 300D with 195,000 miles from an old lady for $1800. my second mercedes, second diesel, millionth german vehicle. interior is great (minimal wear, no tears in mbtex, one or two minor cracks on dash etc,). exterior has a couple of dings, minor surface rust near the gutters, typical paint wear for a car that spent 24 years in the hot florida sun. so far have used this forum (and its shop!) to replace old fuel lines, motor mounts, air filter mounts, filters, oil pan/gasket, turbo drain lower tube and rings, oil separator rings, hood cable, battery tray, oil pressure switch/line, primer pump, valve cover gasket (along with valve adjustment, did a compression test (all 5 in the 300's and within 10%), etc. etc. the list goes on, but the car runs great, has no oil leaks (this week), and looks pretty decent. stripped the interior this past weekend and found some minimal rust (mostly surface) on the rear passenger floor pan, but that is being remedied this weekend. already welded some new metal onto the wheel well underneath the battery tray. pics will come at some point, i promise.

one thing that is driving me batty is that the po's mechanic replaced the metal coolant lines with some regular rubber ones when the original lines rusted through. this is the one non-stock thing on the entire car and i would love to return it to its original form as it is my aim to fully restore this car, but i can't find the pipes anywhere and nobody seems to know what i am talking about. the longest one shares a mounting bolt with the battery tray on the passenger's front wheel well and runs back to the firewall. the other couple hang out around the heater core on the firewall and may actually have connected to the heater core at one time. i cannot tell now because they are all disconnected (but still there). i can take pictures in the daytime if need be, but does anyone know off the top of their head what these could be called or (even better) part numbers for them? i have scoured this site, the interweb, my service manual cd, and a haynes manual and cannot find any mention of them.

thanks!