That is actually very incorrect, I flew quite a few -300s and -400 from 1989 built in that year and previous years and all with EFIS
You are correct
oceancrosser, my bad. The 300 EFIS was certified in July 1986. Here is the link:
The Boeing 737 Technical Site
But, the 300 was first delivered in 1984 & several hundred had been built before EFIS was available. For fleet commonality, many of these airlines continued to order non EFIS 300's, 400's, & 500's long after the glass was available.