@ Wyvern - they used a Gardner 6LW - the only difference between the Gardner 6LW used in lorries and the railcar 6HLW is that the 'H' stood for 'horizontal' so the sump and engines mounts are changed to suit.
With a 6HLW the main things you have to watch out for are the fuel pump, which needs to be kept free-running and properly calibrated or you'll produce enough white smoke to camouflage it; and as it's the horizonal version, keep the oilways clear and watch out for signs of oil starvation in the top end.
A fitter I once knew (and who I think wasn't a fan of Gardner engines) said "you think you've put a Gardner back together again but you've still got half a day's work to hang all that Christmas tree stuff off it..." What he meant was that a Gardner engine is a block, then absolutely everything from throttle linkage to six individual lift pumps gets hung on to it - so make sure all the attachments are tight and using spring washers.
Hope that helps
Paul
