wanted oil cooler for caterpillar D4 s/n 5T2984 year 1945 must be good.

If this is holding you back from running, you can bypass the leaking cooler by connecting the 2 lines together. There are a lot of Posts on this subject. The general consensus is that the engines will not ever work as hard as designed plus modern oils are designed for higher temperatures along with the fact that CAT sent out a Bulletin a long time ago stating it is acceptable to bypass on the smaller older D2 and D4 series tractors.
If you are determined to find one, while using the SEARCH function in the upper right hand of the screen Search for the D4 that was getting parted out this past Winter(?).
Hope this Helps You get it Running!
drujinin

I bypassed my 7U years ago and work it in hot weather. Has never been problem.