I know that radiator well after having built one for a full size Holt 75. My buddy Alan sold one at his auction that we had reseurrected. We wound up making new tracks and few other bits in the process. I can scan and post some prints if there is interest. Your model looks to be amazingly true to scale. I also have a book on early Caterpillar (Holts and Best mostly) with lots of photos, I can get you the info if you need more reference. Fantastic job!
Brian
Brian