i have a radiator leak and it's probably the original or at least very old part (70 sb w/ 307). The rip off radiator shops want to charge more to repair than i can buy a new one. I'd like to replace the 20" with a 28". My problem is the mounting bracket. year one says their bracket only works with their radiators, which are much more expensive than an aftermarket radiator. Has anyone done an R&R to their radiator, and are there any hints on mounting brackets, cushions, size and hoses?
thanks!
x overheating in mississippi

Sounds like you need to do some shopping. I put a heavy duty 4 core affair into my 64 and I got it very reasonably priced. You might find that a new one with the heavy duty setup will suit your requirements, because it will work at 100%. Also it will be much easier to get hoses etc. I had to remove my "shroud" due to thickness and a clutch fan and it works very nicely.

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The proud owner of a Canadian 64-SS with ZZ4 Power!
Team Chevelle Gold Member #37
Canadian Classic Chevelles & Beaumonts Member #350

yep i'm thinking a 4 core with the smaller length 20", but i wonder if the mounting bracket will hold. i'm adding a clutched fan but am concerned about not having a fan shroud.

First off you will ned to buy a fan shroud if you do not have one, no matter what radiator you get it will not cool properly without one. The 4-core radiators usually have a fatter tank so the mounts on the radiator support (bottom) and the hold down plate (top) need to be changed. I would go with a 3 core that fits your existing brackets, I have a high efficiency 3 core and it cools my big block plenty and it was only $200 brand new.