"Teacherjh" wrote in message
...

I wish they'd use new numbers more often rather than letters.
We already have the 172 R, the 172 G, the 172 RG, the
172 N, and so forth, with the letters seemingly arbitrary (or
at least overlapping in meaning)


They did. They went in the order of the alphabet. In the late 70's or
early 80's the 172 also got the name Cutlass. The 172RG was also named
the Cutlass RG