I believe "T203" was taken from the paper label inside the cabinet? In the Sams T203 is the pincushion transformer. If it is indeed the tripler, Sams says there were 2 versions. Some used Zenith part number 212-142-01 while others used one that was combined with a focus bleeder, part number 212-141-01. I can't vouch for this company, but they list both part numbers (but may not stock them?)
http://www.ued.net/catalog/cat_item_idx_1899.html
Somebody on here might have one in their stash, as well.