The frame's been the same throughout the years. I think the problem you have is due more to the individual windshield (or batch from whence it came) you have.

There are basically 3 types of windscreen: the rubber-fitted one (140 through 1968), the glued one (140 from 1969 and 240 through about 1990 I think) and the "flat trim" one (240 from 1991 if I recall correctly). The latter is only available tinted, the former are available both tinted and untinted.

So yes, if it annoys you, by all means get a new one. You might even consider upgrading to the modern looking 91- for slightly less wind noise and less chance of leaking. I know I will once I start restoring my '68 145.

Bram