Can't be much help here - we used to have one and from memory, they're closer together at the top (where they join the hull) than at the bottom but I can't remember actual numbers. If you don't need to know very accurately, I might have an old photo I could try and scale. I don't know if that helps but you might have to post which measurement you were after.
Rabbie
There are three people advertising Leisure 17's for sale in the clasified adverts December issue of PBO all of them have phone numbers. I could PM them to you if you havn't got a copy of it.
The keels of my Leisure 17 sit in channels with an outside dimension of 53 inches across, the channels are made of quarter inch steel, therefore the internal dimension is 52.5 inches. The keels fit comfortably in these channels. Hope this helps.