3.0 CRD Intercooler Upgrade?

[BillsGU]

So to ask a dumb question, if I remove the IC, block one end and submerge it in a bucket of water, & blow air into it, that should tell me if it's leaking, correct??

If you do that you are likely to rupture it with too much air pressure - unless you use a regulator. Easiest way is to block both ends and put it in a tub of water and see if any bubbles emerge.

But as mentioned above - you should see oil stains on the IC where it is leaking.