This is one for retired trainspotters - those who in the 1960's would instantly recognise that 65J was the shed code for Stirling South engine shed (Changed from 63B in 1960). Engine sheds were where you could see lots of engines all at once so they were goldmines to spotters. Sunday was the day to go because most railway companies operated on a 7 day rota that returned engines to sheds on Sunday to begin the next week. There they simmered until their work began again and if you were lucky you could get into the shed and spot all the locos - the official way was to apply for a pass but sneaking in the back way was also possible. My own home shed was 9C Macclesfield on the LMS region and we used to nip in via the goods yard and then peer round the corner of the shed itself to identify the locos inside. I can imagine the same tactics were employed by young lads here at Stirling. This shed was the Caledonian Railway depot but there was once another staging post for the North British Company at Shore Rd just to the North of the station. That shed closed in 1958 but this one stayed open until 1966 just before the demise of steam traction.
Stirling was an important junction and provided engines for several services - local ones to Dunblane, Alloa and out across the Forth valley to Aberfoyle and as a mainline stopping point for Perth, Aberdeen, Inverness and until the line closed to Oban. I would have loved to be around then and see a Double headed Caley Bogie toiling up Glen Ogle across the viaduct.
Ah - back to the cache. There are many preserved locomotives similar to those that would have passed through Stirling or based here. The list includes: The Jones Highland Goods, Glen Douglas, D49 class The Morayshire, A3's like Flying Scotsman, A4's like Mallard, Caley Tanks like the one still running at Bo'ness, K4 class The Great Marquess which visited Stirling on the reopening of the Alloa line in 2008, K1 class The Lord of the Isles on its way to Fort William and finally the ubiquitous Black Fives ( One now named George Stephenson) which were the mainstay of the Oban service often double heading heavy boat trains or excursions. Incidentally the elegant Stirling Single never made it this far but you can't ignore it because of its nominal connection.
So take a deep breath and access that smell memory for the coordinates of the cache. On the North Road of the shed line up: Gordon Highlander, Lord of the Isles, Jones Goods, George Stephenson, Maude & Morayshire. Now multiply them by 117 and add 9223.
On the West Road of the shed line up Flying Scotsman, Caley Tank, Great Marquess, Green Arrow, Glen Douglas & Mallard. Now multiply them by 20 and subtract 778.
Robert Burns finds this one first though he predates the railways by a century or so!
You can check your answers for this puzzle on Geochecker.com.