Dating fender deluxe reverb amps by serial number
Two types of blue and silver grillcloth were used on the early silverface amps.
The first type (1967 - early 1968) had no silver metallic threads and the second is the more familiar cloth with the silver metallic threads and a much greater texture or thickness than the first type (mid-1968 onward).
The aluminum trim was retained through late 1969, though we speculate a few early 1970 amps may have had the grill trim as well.
Interestingly, some silverface amps from early 1968 have 16 inch tilt back legs with serial numbers on one or both legs.
Many blackface amps were stamped with a date code on the inside of the chassis.