I recently replaced my bus's entire cooling system and had Atlas Radiator in Santa Fe Springs CA make me a new core. If your bus is in SoCal that's an option for you. Atlas made me a 6-row core a few inches taller than the old, with more tubes per row, dimpled tubes, and much denser serpentine fin count, all copper and brass, for about $1800. I reused my tanks after I had them powder-coated, and along with a new custom-made fan and hydraulic fan motor, a new hydraulic/PS pump, a new transmission cooler with fan, a new hydraulic filter, and much much else, I think I've finally got my overheating problems under control.
There's a wholesale radiator manufacturer in San Bernardino CA called Thermal Solutions Manufacturing, and their website has a lot of useful info on cores, tanks, gaskets, etc. They have a catalog online that lists radiator sizes and specs for pretty much any truck or bus ever made in USA. I remember seeing some different sizes of radiator for mid-engine Crowns mentioned, maybe one for smaller Cummins and Detroits and one for Big Cam Cummins?
You may be lucky to find a matching used radiator from a Crown being scrapped, as long as it's not a CARB scrap job. However, it's a crapshoot if it's any better than what you have now, and for all the work involved I feel it's better to get a new core, then you won't have any problems for the next 20 years or more.
Finding 11.00R20" tires will be a challenge! Are they the same diameter and RPM as 12R22.5"? Maybe you can find usable take-offs and wheels from a school bus being scrapped, but they would have to be the same ply rating and load range as your present tires to be safe, and the same diameter to keep your speed the same as now.
John
