Both the lacings are missing on my '21 with a wood firewall. I ordered both from Langs. Now , even after a search on here, I'm unsure how they should be installed. I thought the lacing for the shell would be put on using split rivets like the ones used on band linings. Correct? Is there a metal strip missing from the firewall where the lacing goes?
The 3/8" lacing on the radiator shell is simply laced through the holes or slots in the shell. No rivets.
Use the same 3/8" radiator shell lacing for the firewall - the 5/8" hood lacing sold by the vendors is too wide and interferes with the hood hinge notches in the firewall. There should be three metal caps on the wood firewall - one on top with a drip edge and one on each side below the notch for the hood hinge. The lacing and caps are attached with nails. (Note that in my examples, the 1917 top cap does not have a drip edge - that came later.)
See this thread: