Hello Dimis,
This post is from the SAAC forum Dan Case aka rr64, Dan has collected and comprised information regarding Webers and has a fairly accurate way of dating or identifing the time period of Italian Webers From 48IDA, 48IDA-1, through 48IDA-4, and serial nimbers. I have posted on that thread as well. My forum name there is SFM5S000. Read through it.
GT 40 48 IDA Manifold and Linkage
Earl J