I took apart both heater boxes, one from my 60 and the one from the 61 parts car to use the best pieces to put together the best box possible with parts on hand. Looks like the sheet metal from the 60 won by a long shot while the case from the 61 is a winner hands down. Both cores were shot so a new core was purchased from Melvin's Classic Ford Parts. The case came clean after repeating cleaning with Greased Lighting and a paint brush used to get in the corners then rinsed well with water. Lacquer thinner and steel wool finished the cleaning process. Three or four coats of matte clear coat was sprayed on the heater case. The metal pieces got to visit the blasting cabinet then a coat of etch primer and a couple coats of silver. The date code on the 61 box in white ink stamp reads W-1-E-C, The date code on the 61 plenum also in white ink stamp reads Y-1-E-B. I do not see any date codes on the 60 box. I'm going to try and restore the paper plenum from the 61 and if that doesn't go as planned I got the plastic aftermarket plenum to fall back on after I fit the little door. Both motors making a bad noise so I will be replacing the one that the fan comes off the easiest, hopefully without getting bent.
The driver's fresh air box from the 61 is different than what came on the 60. The 60 was mounted to the cowl with screws whereas the 61 used two J-bolts. The 61 also has a hook for the wiring harness and an extra rivet holding the two halves together. No date code on the 60 fresh air box but the 61 has white ink stamp Y-1-E-B. I don't know that the Y stand for but the 1 is the year and E is the month (61/May) I'm guessing the B is second week of the month. This date will align with the May 19th date on the data plate on the driver's door. Both fresh air boxes were in need of fiberglass repair where the door hinge attaches and/or where the screws go to hold the box to the cowl.