It was not stated in the thread that 54 gauges are 6".
Their products look good.
Your link is to 47-53 gauges (that you state are 5" diameter). They will, of course (I presume) work fine in a 1947-1953 Chevrolet/GMC dash.
The originator of this thread, and I, were specific about 1954, which has 6" diameter gauges.
"Does Classic Instruments sell original-fitting 1954 Chevrolet Truck gauges?
A link to the parts would be helpful."
Sorry, I was not clearer. 6" gauges are used in 1954 trucks. It's not a matter of standards; it's a matter of fitting.
"Want to try and avoid all the aftermarket inserts and adapters."
