welcome to the site fjbully, as a mechanic i would personally recommend the 3 row aftermarket aluminum radiator (moline make a very dependable one along with others that specialize in foreign an discontinued models). several reason for this, you don't have an automatic trans so that eliminates the need for the extra cooling one might need while towing or doin some serious climbing, next is to much cooling can be bad but not detrimental, vehicles are designed to run at a certain temp and if they can't reach the will have a tendency to run not so good, aluminum collects and dissipates heat much more efficiently than the old stock brass radiators and cost less than have of the brass, this of coarse is just my opinion albeit influenced by over 30 years of turnin wrenches and makin a good livin doin so. good luck with any way you decide to go, post some pics soon, i love the old fj40s

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POLICAN4912