Here's the first possibility: former England youth international and Tranmere traniee David Raven. It has been rumoured on a certain Rovers message board and been announced on the official Liverpool website that Tranmere are intrested in loaning Raven for one-season. Raven would be a good signing too. He is an excellent tackler and passer of the ball and also has league and cup experience.
Nextis another Liverpool player, John Welsh. Welsh can play all across the back line and midfield and would be an excellent signing just for his versitility, let alone his superb passing ability and tackling ability. Plus he has both League and Champions League experience.
Another option would be ex-Rovers player Sean Connelly. When the Irish man was released by Rovers last summer, he signed for Rushden and Diamonds. This season, he has been released by the League Two club. Connelly is a great header of the ball, and passer and tackler and can also fill in at center back if needed.
Whoever signs for Rovers to play at right-back is going to have a lot to live up to. Ryan was a wonder-kid lets face it. He could do everything to an excellent standard. Pass, tackle, shoot, penalties and free-kicks, crossing and heading. There was not alot that Ryan couldn't do. So whoever replaces Ryan, has aot to do to fill the crator that Ryan has left.