The gap between the wooden floorboards seems a little arbitrary even among same models as John found above, his being no more than a slit. My car was a little better although still tight. I managed to put an extra bend in a solid grease gun extension that allows, with gun upside down, to just connect to forward UJ spider nipple, shown in Jon's image, and at the right angle. Managed to grease same a couple of times now. Note the sliding joint nipple immediately aft, hidden on my car by a captive protective cap, that also needs grease.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone