Does anyone know what type/make/model the heatsink was used on the roof rack? The one towards the rear near the radome.
It’s unknown. Basically, it’s two identical heatsinks connected back-to-back. It also appears on the Ecto-1A. I have been trying to ID it for years. I think they may have either come from the inside of a massive computer workstation from a company called Burroughs or out of equipment found on a Lockheed P3 Orion surveillance aircraft, but I don’t have the proof.
I’ve got a correct looking vintage heat sink for the Ecto-1, but I have no clue who makes it?
James
Let’s see it?
This is a picture of the correct heatsink on the Ecto-1. It’s actually two separate heatsinks bolted together and not a single one. Plus, the way the fins are designed possibly makes it proprietary.
Actually, that is the heat sink that got replaced in the “first” restoration. Probably around 1986 - 1988, just before Ghostbusters 2. And it’s the one they’ve kept on the car ever since. In fact, that is the same kind of heat sink that is used on the Ecto-1A.
The true original heat sink is like the one I have. Here are some pictures of the original black heat sink on the original filming car.
In this picture, just above Ray’s head, the original black heat sink can be seen:
Very happy you find one 
I happened to be at a small town surplus store, and they just had this lying on the shelf
Fantastic find!
Isn’t the original black heat sink present here on the original Ectomobile in the opening of Ghostbusters 2?:
Sadly no, it looks like the heatsink on Ecto-1 at the start of GBII was the version 910dohead posted earlier in the thread:
It appears my eyes have deceived me, but upon looking more closely, I can tell that it is not the original heat sink.
Yeah, James/DeLoreanDMC81 is 1000% correct here. The heatsinks were swapped out sometime before Ghostbusters 2. The heatsink that’s on the Ecto-1 seen in the opening of the second film is the one that’s currently on the car now. Learning this blew my mind and still amazes me that there’s always more to learn about the props. Some 35+ years later and we’re still figuring this stuff out.
Taking a break from working on a Saturday; my stab at an ID of the heatsink that was posted by DeLoreanDMC81 and GraygoryGruesome. Guessing that a large heatsink like this is/was designed with a particular component or class-size of component for particular application. I found multiple very similar designs from different companies. My best guess:
#60105 profile from AAVID Thermalloy, now part of Boyd Corporation.
Aavid Thermalloy catalog page:
https://info.boydcorp.com/hubfs/Thermal/Air-Cooling/Boyd-Aluminum-Extrusion-Selection-Guide.pdf.
Go to PDF page 53 and look at #11
Listing from the Boyd Corporation:
https://www.boydcorp.com/files/part-documentation/extrusion-60105-drawing.png
The folks working on the Northern Illinois Ghostbusters 2 Ectomobile recently acquired what appears to be the correct heat sink:
It’s being sold by our own 910dohead here in the for sale section.
Yeah, they need a little cleanup but will look great afterwards. I just got around to cleaning off the set I have for myself. They’ve most likely been sitting in dirt since date of manufacture, so who knows for how long?