Just a front view? Looks like it might be a molded commercial dish, perhaps a Prodelin?
From that view, it appears to be about a 1 meter Ku dish, and not a BUD.
Mostly, the Ku dishes are offset feed, and the "round" ones are a little taller than they are wide.
So, measure the width, as that is the effective aperture (or close).
Generally, the stamped metal import dishes will be measured by their height.
While not wrong, that's not consistent with the commercial molded dishes, and may be one reason they generally perform a bit lower.
I use both, so whatever you have can be put to good use.
If the Ku dish is elliptical, and far wider than tall, then the dish width is an indicator of the beam width.
The height is interesting, of course, and you should mention that too, for others to recognize what you are talking about.
But again, the width will be the main indicator of performance.
edit: oh, gas station dish? That'd be a nice commercial Ku dish! woo hoo!
Show us some pix of the back side, the mount, and where the feed horn arms attach.
Should be a real gem for you! Especially if you got it all (incl the LNB and feed horn)
For an offset parabolic dish (where the dish is heigher than wider) I would always use the width or short length. The reason is due to the offset, the dish appears round to the satellite in the sky, or to the LNB(F), but the width is the width that the satellite "sees". This would (approximatelly) be the effective aperature of the dish.
Don't waste your money on a conical scalar the flat will work better on a offset dish larger then 1 meter. And if your thinking of one of those C/Ku LNBF you will be disappointed, they are designed for PF.