53 and 55 6v or 12v?
Both are 6-cylinder engines?
If you want a 12v powered timing light, you might have to use a 12 external battery to power the timing light with a 6v truck.
I have an old neon timing light that works with 6v/12v (I think that most/all xenon lights need 12v?).
Actually, on my 235 and 261 engines, I time to maximum vacuum at idle, Then, I fine adjust using
the "ping" technique.
