Sorry it took a while to get back to you but it isn't a 'quick' project.
Small boat car is right but with the 'Hi-Load' optional Torlon bearings. As I mentioned before, unless you can procure a retrofit to your old traveller car you will be buying the new "CB" cars with Captive Bearings. This is great because you don't need that little blue piece of plastic but what it does mean is you have to replace the track. The CB cars have a stainless bearing retainer that requires a new CB-type track. Additionally, as mentioned before Harken has shifted from their original hole spacing of 4" centres to 100mm. mkVs were installed with the 4" centres so unless you want to fill and then drill new holes (might not be a bad idea) you need to order the RETRO track with a slight premium and a huge delivery time. Removing the original track requires you to pull all those round 1" diameter plugs down and also pull the electrical panel for the centre 3 screws. After its removed trim the new track to fit the existing. I had found that the outer screwholes weren't drilled. The ends will have to be drilled and taped for the end cap (Hi-Load Red Ones). Installing the track is nothing fantastically complex but very fiddly. The 10-32 nuts and washers are hard to replace by sticking your finger up the 1" hole in the liner. As I installed the track I was caulking the bottom of the track around the screws with 5200. The residual guck on my fingers ended up helping hold the nuts and washer on my finger as the screw engaged the first threads.
Once the track is on you simply slip that expensive little car onto the track, rig the control lines as per the diagram and you're set. I did find that the traveller control lines were too short compared to my previous setup which I thought was 3:1.
Not sure if I've missed anything, hope this helps.
Mk V - Hull 154