I have a 1965 Buick Wildcat (Base) with the 401 Nailhead engine with a leaking factory radiator.

Most of the part interchanges suggest this can be replaced with a radiator common to many GM products from 1963-1990. However, this is incorrect as all the connectors on the suggested replacement are on the opposite side from the stock radiator which has the filler, trans lines, and outlet on the driver's side. This appears to be a quirk common to '64-'66 Buicks with the 401 and 425 engines.

There are approximately two vendors I've found who offer a correct replacement radiator with the proper configuration, but the price tag is pretty steep ($650-$750) which is close to what I'm being quoted from one of the few guys in my area that still does recoring ($700).

I wound up talking with a tech at Holley Performance who pointed out there is an aftermarket radiator for Ford products from 1979-1993 which is the same overall size and connection placement as what I'm looking for -- at half the price.

The drawback is the sizing for some of the connectors isn't identical:

Connection GM Factory Radiator Ford Alternate Radiator
Core Size 17 x 28 1/4 17 x 24
Inlet 1 1/4 1 1/2
Outlet 1 1/2 1 1/2
Trans Cooler 1/2-20 Straight G 1/4 1/8-27 NPT

I'm not especially worried about the slightly smaller core size, but the smaller inlet gives me pause and the smaller size of the transmission cooler line connections for the TH400 has me outright concerned.

Apart from the obvious need for adaptors, what are the practical considerations of using a radiator with these smaller connections? Should I be worried about the smaller connections, especially for the trans cooler lines?

  • I suppose there's also the option of getting the "backwards" radiator and swapping out the hoses and trans cooler lines. That radiator runs about $350 -- just slightly more than the Ford alternate -- which would still be less than the matching reproduction or recore. Sep 30, 2022 at 17:57

2 Answers 2


While not answering your question directly, couldn’t you just get your original radiator re-cored?

There are generally lots of local businesses that re-core radiators. This is usually a lot cheaper than a replacement radiator.

Doing this will keep the original headers and hence the correct connectors.

  • I've talked to my regular mechanic who has a '49 Chevy and he himself is looking for someone local who still does recoring. I've also done a Google search in my area and turned up exactly two places that specify they do recoring. One is more than an hour away and has a website that doesn't instill confidence, The other is half an hour away and comes across as extremely competent, but he's quoting $700. Sep 30, 2022 at 17:33

Unless you are REALLY stressing the engine, I suspect you will be just fine. And what do I mean by stressing the engine?

  • Extremely hot weather location
  • Towing a heavy trailer
  • Very mountainous terrain
  • Blocked radiator airflow (eg Jeep with Bull bar & winch)

Also, make sure your cooling fan is performing correctly. You should be just fine.

  • This is pretty much what I've been thinking in terms of engine cooling. Would this apply to the transmission cooling as well? Sep 30, 2022 at 17:29
  • @FDryer the radiators on RockAuto have the fittings on the wrong side also. Sep 30, 2022 at 22:31

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