Bill, I have (2) '64 fuse blocks, the original and a spare I collected because it was in better shape.
The flashers are Ideal Corp. No. 536 and NAPA No. 552 respectively. The Ideal one is marked "Heavy Duty FLasher" and is a taller unit.
Neither is original.
I have NO IDEA what the 383636 unit looked like, have yet to find one. But I suspect it was all but identical looking to the 383639 which seems to be pretty common. The 383636 may have been taller than a 383639, not sure.
The 383636 was eventually superseded by 383637.
Searching around, my guess is that the O.E. flashers were mainly Tung-Sol brand. However, they may have also made use of an alternate brand.
No doubt in my mind they were metal.
If Tung-Sol brand, most likely with stamped nos. on them including a date code.
The tops were embossed to read "MFD TO J590-61" around the word "SAE". Most likely this was true of the '64 flashers. They did not get marked "D.O.T.", apparently that came later.
There seems to be some debate as to whether and when the cans were painted. Earlier flashers may not have been painted and not clear when they started painting them, if by '64 or perhaps '65. Judging from what I think are NOS late '50s, early '60s Tung-Sol flashers, the cans look to have been plated, not painted.
If the O.E. flashers were painted cans and not plated, I can only guess this was done to shave a penny from the cost perhaps.
It occurs to me that the painted ones may have been the Service Replacements, especially if the painted ones cost MORE. But I am only guessing.
I am not at all certain but it is possible that the 383636 was Tung-Sol No. 536 and 383637 was Tung-Sol No. 552. I say this in part because it looks like at some point Tung-Sol offered a 552/536, meaning a single unit was suitable to replace either no. I'm guessing the specs were close enough between the two that it didn't matter.
We discovered with the '64 O.E. Horn Relay had two very different appearing types used in production, just depended on which supplier's unit was being installed in a given build, the Assembly Guide allowed for either.
That could also have been true of the Flasher. The alternate (if there was one permitted) was likely produced by Signal-Stat. Very different in appearance.
GM may have chosen to only offer the Tung-Sol brand for Service Replacement, doesn't mean they didn't install the alternate in production.
Posting this as food for thought while we all wait for somebody to say they have the original still in their '64 to study.
Me, I always have used turn signals, and have had to replace flashers. What we need is the guy who never bothered to use his signals, so the flasher never wore out!
