Chris,
I think the credit should go to Jonsey for supplying us with the service tech bulletin.
Here's where it gets complicated...or maybe not...since the 420 & the 338 were replacements for "Hot Cranking" problems associated with the 361 it would be difficult for anyone to say, regardless of dates on these replacements, if these would be correct applications for anyone trying to assemble their L48's with "#'s parts"...just one guys opinion.