Author Topic: fan shroud interchange  (Read 1354 times)

Offline Cs Tree Needs

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fan shroud interchange
« on: May 06, 2019, 10:59:14 AM »
81 c3500 5.7,  manual,  w/o a.c.

what years/models interchange

Offline zieg85

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    • 73-87 GM squarebody extended cab and conversions up to 91 R/V series
Re: fan shroud interchange
« Reply #1 on: May 06, 2019, 11:12:30 AM »
It is more the height of the radiator and how the shroud attaches.  Unless you know the history of the truck what you have may have already been changed.  Do you have a picture or is yours missing?  I do have a 1981 C30 I can take a picture of if needed
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction

Offline Cs Tree Needs

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Re: fan shroud interchange
« Reply #2 on: May 06, 2019, 12:04:53 PM »
i have the old 1, it broke in a couple spots from a meeting w/ a falling 2x8.
i guess common sense tells me to take measurements, but the replacements online didn't show dimensions that i recall.

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: fan shroud interchange
« Reply #3 on: May 11, 2019, 06:20:49 AM »
This is my understanding of the radiator options
- All the radiators are about 28 1/4" wide at the core (measure inside the tanks)
- The cores are 17" high and about 21" high radiators
- Depth (front to back) varies from about 1 1/4" to 2 1/2", depending on the number of cores.  2 ancd 3 core are most common, although on a one ton you might find a 4 core.  You can remove the cap and look inside to see the number of cores.

When you swap radiators to a different height or depth you usually have to change the top metal bracket, and you always have to change the rubber insert in the frame on the bottom and the bracket on the top. If you have the right rubber insert it will fit right over the radiator end and hold it securely.

I used a Jegs Champion 3 row aluminum radiator for my '75, and it fit fine and works very well.  I was replacing a stock 3 row copper radiator, which is probably what you have.  However, my truck used the shorter 17" core radiator, while your truck might have the taller 21" core.  This aluminum radiator cools much better than my old radiator.