The one that I have is for a 10' wide slip. If you go to
www.dockrealty.com it will say if the lift is set up for a 10' a 12' or either. I just sold an 8,000# poly lift through them and then purchased a 12,000# and the everything has been seemless.
I actually talked the installer they use the other day and he said my new lift is going in this week. They also went the extra mile and got a quote from the installer to remove my transom platform from the old lift and refabricate it to fit the larger tanks on my new one.
Hopefully this helps you out.
One other note is if your slip gets a lot of wave action make sure you get a beefier lift. I will tell you straight up that the one I have for sale is not suitable for main channel wave action and would be best back in a cove or in a slighlty more protected area.
Where's your place at?