I have a couple, will dig them out of the shed later and see what's what. On the plus side, I've had the bits blasted and galvanised so they should never rust. The negative, is that the bits are now all mixed up so I'll need to do a jigsaw puzzle before selling them.
There were at several designs available. Most required you to drill two holes through the jacking point (that rectangular lump below the boot), while some had two parallel members that passed either side of it. Then the main bar fitted along the bumpers was straight on some and bent on others. A straight bar prevents you fitting rear over-riders.
By the way, whereabouts are you?
I'm on Anglesey but will be heading to Lincoln next weekend and Bath towards the end of next month if that helps.