Here's one
http://www.amazon.com/Orion-Basic-1-.../dp/B0000XMXF2
but it looks like it's cheap plastic junk .
If you can't find one, I think I have a nice all metal 1.25" rack and pinion focusor with a universial base that I bought for a project that never happened so it's never been used, which is stashed in the back of the filing cabinet somewhere.